A. Pavel. West Liberty State College.
As the median nerve exits the axilla buy 250 mg zithromax mastercard antibiotic resistance peer reviewed journal, it passes inferiorly adjacent to the brachial artery cheap 500 mg zithromax amex antibiotic bloating. A: the ligament of Struthers from an anomalous supracondylar process to the medial epicondyle, which may compress the median nerve. Prior to passing through the carpal tunnel, the median nerve gives off the palmar cutaneous branch, which travels downward next to the median nerve between the palmaris longus and flexor carpi radialis muscles. The palmar cutaneous branch of the median nerve provides sensory innervation to the skin of the thenar eminence and the proximal palm (Fig. As the median nerve passes beneath the flexor retinaculum, which is also known as the transverse ligament, through the carpal tunnel, it is subject to entrapment for a variety of pathologic conditions (Figs. The terminal branches of the median nerve provide sensory innervation to a portion of the palmar surface of the hand as well as the palmar surface of the thumb, index, and middle fingers, and the radial portion of the ring finger (Fig. The median nerve also provides sensory innervation to the distal dorsal surface of the index and middle fingers and the radial portion of the ring finger. Superficial dissection shows the median nerve lies deep to and between the tendons of the palmaris longus muscle and the flexor carpi radialis muscle at the wrist. Carpal tunnel syndrome can be caused by a variety of structural and anatomic abnormalities and is associated with a number of pathologic conditions. While the clinical presentation of carpal tunnel syndrome is consistent, this entrapment neuropathy has many causes and is associated with many pathologic conditions (Table 48. Carpal tunnel syndrome presents as pain and dysesthesias with associated numbness and weakness in the hand and wrist that radiate to the thumb, index finger, middle finger, and radial half of the ring finger. These symptoms may also radiate proximal to the level of nerve entrapment into the distal forearm. Decreased sensation in the distribution of the median 446 nerve of the thumb, index finger, middle finger, and radial half of the ring finger is often present as weakness of thumb opposition. A positive Phalen test is highly suggestive of the diagnosis of carpal tunnel syndrome. Phalen test is performed by having the patient place the wrists in complete unforced flexion for at least 30 seconds (Fig. The test is considered positive if this maneuver elicits dysesthesia, pain, or numbness in the distribution of the median nerve. Wasting of the thenar eminence may be seen in more advanced cases of carpal tunnel (Fig. Patients suffering from carpal tunnel syndrome will exhibit a positive Tinel sign over the superficial median nerve. The Phalen test for carpal tunnel syndrome is performed by having the patient place the wrists in complete unforced flexion for at least 30 seconds. The test is considered positive if this maneuver elicits dysesthesia, pain, or numbness in the distribution of the median nerve. The numbness and dysesthesias of entrapment or compromise of the palmar cutaneous branch of the median nerve are limited to the proximal palm and thenar eminence and motor findings are conspicuously absent (Fig. The overlap of symptoms of carpal tunnel syndrome and entrapment and/or compromise of the palmar 447 cutaneous branch of the median nerve can lead to many clinical misadventures and the use of ultrasonography and electromyography can help solidify the clinical diagnosis. The clinician should entertain a high index of suspicion for iatrogenic damage to the palmar cutaneous branch of the median nerve following carpal tunnel surgery if the patient complains of persistent numbness in the proximal palmar triangle and over the thenar eminence. To perform this assessment, the patient is placed in the sitting position with the elbow flexed to about 100 degrees and the forearm resting comfortably palm up on a padded bedside table with the fingers slightly flexed which will relax the flexor tendons. With the patient in the above position, the distal crease of the wrist is identified (Fig. A high-frequency linear ultrasound transducer is placed in a transverse position over the distal crease of the wrist and an ultrasound survey scan is taken (Fig. The median nerve will appear as a bundle of hyperechoic nerve fibers surrounded by a slightly more hyperechoic neural sheath lying beneath the flexor retinaculum and above the superficial flexor tendons (Fig. The median nerve can be distinguished from the flexor tendons by simply having the patient flex and extend their fingers and observing the movement for the tendons. The flexor tendons will also exhibit the property of anisotropy with the tipping of the ultrasound transducer back and forth over the tendons. Color Doppler may aid in the identification of the ulnar artery so it can be avoided when performing in plane needle placement (Fig. After the ulnar artery is identified, the ultrasound transducer is slowly moved medially until the median nerve is again easily identifiable in the transverse ultrasound image. B: Proper transverse position for the linear high- frequency ultrasound transducer to perform ultrasound guided injection for carpal tunnel syndrome. Transverse ultrasound image demonstrating the median nerve lying above the superficial flexor tendons. The ulnar artery is identified on transverse ultrasound scan so it can be avoided during needle placement when injecting the median nerve at the wrist. After the median nerve has been identified, a quantitative assessment as to the shape, size, echogenicity, echotexture, and overall appearance of the nerve is carried out in both the transverse and longitudinal planes. On ultrasound, the nerve fibers of the normal median nerve are clearly identified and symmetrically placed between the hypoechoic endoneurium. The epineurium should appear as a hyperechoic margin surrounding the nerve fibers. The shape of the median nerve in the transverse plane should be ovoid, without asymmetry. Enlargement and loss of ovoid symmetry is a characteristic ultrasound finding in carpal tunnel syndrome (Fig. When the median nerve is entrapped at the carpal tunnel, there is often a loss of the normal intraneural fascicular architecture secondary to intraneural edema (Fig. These findings will become more evident as the entrapment of the median nerve persists (Fig. The median nerve is then evaluated for swelling and flattening at a point just proximal to it passing under the flexor retinaculum and entering the carpal tunnel. Often an inverted notch sign is identified, which signals an abrupt change in the diameter of the median nerve secondary to compression and strengthens the sonographic diagnosis of carpal tunnel syndrome (Figs. The flexor retinaculum is then evaluated for thickening and for extrinsic compression from external masses including ganglion cysts (Figs. The contents of the carpal tunnel are then evaluated by abnormal nerve configurations, e. Color Doppler of the median nerve will help identify vascular abnormalities within the carpal tunnel as well as the hypervascular changes often seen in median nerve entrapment at the carpal tunnel (Fig. Normal transverse ultrasound image of the median nerve at the distal wrist crease. Short axis color- optimized image of the carpal tunnel demonstrates the normal sonographic appearance of the median nerve: hypoechoic with an echogenic margin of fibrofatty tissue. Ultrasound appearance of the median nerve in patient with moderately severe carpal tunnel syndrome. Note the loss of the normal intraneural fascicular architecture secondary to intraneural edema.
The data gleaned from these interventions can help the clinical formulate a rational treatment plan for the patient buy on line zithromax antibiotic resistance fitness cost. Brachial plexus paralysis of a dominant arm due to hematoma associated with internal jugular vein cannulation purchase zithromax 500 mg on-line bacteria urine hpf. Diagnosis of closed injury and neoplasm of the brachial plexus by ultrasonography. To perform ultrasound evaluation of the brachial plexus, place the patient in the supine position with the head turned away from the side to be imaged. The cervical nerve roots can be imaged with ultrasound as they emerge from between the intervertebral foramen, although magnetic resonance scanning may provide more useful information at this level (Fig. High-frequency color Doppler ultrasound image of brachial plexus at the intervertebral foramen plane in healthy adults. C6–7 nerve roots traverse the intervertebral foramen and project outward and downward (arrows). Following the brachial plexus distally to the intrascalene, the plexus is best imaged at this level by having the patient raise his or her head against the resistance of the clinician’s hand to identify the posterior border of the sternocleidomastoid muscle. In most patients, a groove between the posterior border of the sternocleidomastoid muscle and the anterior scalene muscle can be palpated (Fig. Identification of the interscalene groove can also be facilitated by having the patient inhale strongly against a closed glottis. Once the interscalene groove is identified, the C6 level is identified by palpation of the cricothyroid notch. After preliminary identification of the approximate location of the brachial plexus using surface landmarks, a linear ultrasound transducer is placed over the previously identified location in the transverse plane and a survey scan is taken (Fig. The superficial triangular- shaped sternocleidomastoid muscle is identified, and then the anterior and middle scalene muscles are identified beneath it (Fig. The roots of the brachial plexus lie between the anterior and middle scalene muscles and will appear as hypoechoic round or slightly oval multifascicular structure with a hyperechoic perineurium. The internal jugular vein and the carotid and vertebral arteries can be located using color Doppler (Fig. The clinician then moves the ultrasound transducer in a slightly cephalad or caudad direction until the nerves of the brachial plexus can be seen to “align” within the sheath of prevertebral fascia. The transducer is rotated into the longitudinal plane and the plexus is evaluated in the long axis (Fig. The interscalene groove lies immediately behind the lateral border of the clavicular head of the sternocleidomastoid muscle at the level of the cricoid cartilage (C6). Identification of the groove can be facilitated by 157 having the patient inhale against a closed glottis. Proper placement of the linear ultrasound transducer over the previously identified margin of the sternocleidomastoid muscle. Transverse ultrasound image of the brachial plexus at the level of the cricoid cartilage (C6). Transverse color Doppler view of the brachial plexus and the internal jugular and carotid artery. High-frequency longitudinal ultrasound image of the brachial plexus at the intrascalene level. The transducer is returned to a transverse plane and the brachial plexus is imaged as the transducer is slowly moved distally to the supraclavicular region (Figs. The anatomy of the brachial plexus and surrounding structures at the supraclavicular level. Note the relationship of the brachial plexus to the subclavian artery, superior border of the first rib, lung, and anterior and middle scalene muscles. Proper placement of the linear ultrasound transducer over the previously identified margin of the sternocleidomastoid muscle at the supraclavicular region. The brachial plexus, the lung, subclavian artery, and the first rib are identified (Fig. Color Doppler can be used to further delineate the subclavian artery and other vascular structures (Fig. The transducer is rotated into the longitudinal plane and the plexus is evaluated in the long axis. Transverse ultrasound image of the brachial plexus at the level of the supraclavicular region. Transverse color Doppler view of the brachial plexus (arrows) and the subclavian artery at the supraclavicular level. The transducer is returned to a transverse plane and the brachial plexus is imaged as the transducer is slowly moved distally to the infraclavicular region (Fig. The ultrasound transducer is then rotated so it is aligned with the superior aspect of the transducer pointing at the acromioclavicular joint and the inferior aspect of the transducer pointing at the patient’s ipsilateral nipple, and an ultrasound image is obtained (Figs. Placement of the transducer in this position will provide a short axis view of the axillary artery and cords of the brachial plexus with the artery appearing as a round pulsatile structure surrounded by the medial, lateral, and posterior cords of the brachial plexus (Fig. The axillary artery, the cords of the brachial plexus, the intercostal muscle and the pleura and lung, are then identified. Color Doppler can be used to further delineate the axillary artery and any other vascular structures (Fig. The transducer is rotated into the longitudinal plane and the plexus cords and vessels are evaluated in the long axis. To reach the cords of the brachial plexus at the infraclavicular level, the needle must traverse the skin, subcutaneous tissue, and pectoralis major and minor muscles. To evaluate the brachial plexus at the infraclavicular level, an imaginary line is drawn from the acromioclavicular joint to the ipsilateral nipple to aid in placement of the ultrasound transducer. Proper placement of the linear ultrasound transducer at the infraclavicular level. Transverse color Doppler view of the brachial plexus and the axillary artery at the infraclavicular level. As the brachial plexus is being imaged with ultrasound, care must be taken to identify abnormalities, including tumors, abscess, nerve trauma, inflammation, and other causes of brachial plexus compromise (Figs. Some of the roots are globular in shape and the others fusiform (right and left coronal sonograms were fused photographically and displayed vertically). A: the tumor appears on ultrasound as a solitary rounded mass (S) with smooth contours and hypoechoic texture. Diffuse infiltration of nerve roots by metastatic breast carcinoma associated with postirradiation fibrosis. A: the right coronal sonogram shows normal appearance of C5 and C6 roots of the brachial plexus (arrowheads). B: the left coronal view in the same patient shows a diffuse hypoechoic thickening of the same roots (arrowheads). The caliber of the affected roots is significantly enlarged in comparison with the contralateral nerves and a loss of the normal nerve tapering distally can be noted (same scaling factor on both images). High-resolution sonography detects extraforaminal nerve pathology in patients initially diagnosed with cervical disc disease: a case series.
In bone marrow transplantation purchase zithromax canada virus respiratorio, Microchimerism is the establishment in a transplant recipi- not only is immune reactivity against donor type cells an ent of passenger donor hematopoietic cells that accompanied obstacle to bone marrow engraftment buy 100mg zithromax bacterial 2 hybrid, there is also the prob- the solid organ transplant. The term commonly refers to the trans- Full chimerism is the state in which all of an individual’s fer of a particular gene from one background strain/stock to hematopoietic cells are of donor origin. This results when a an inbred strain via multigenerational matings to the desired bone marrow or hematopoietic stem cell transplant is per- strain. Breeding an F1 hybrid with either one of the strains formed following myeloablative conditioning to eliminate all that produced it. The rejection rate in hematopoietic cells in the bone marrow are eliminated corneal transplants depends on vascularization; if vascular- through the use of aggressive chemotherapy and total body ization occurs, the cornea becomes accessible to the immune irradiation, causing depletion of immune system cells from system. This procedure is necessary prior to hematopoietic cell with topical steroids to cause local immunosuppression. Certain anatomical sites within the animal body provide an Mixed chimerism occurs in a non-myeloablative conditioned immunologically privileged environment which favors the hematopoietic cell transplant recipient, who has received a prolonged survival of alien grafts. The recipient’s surviving hematopoietic ment of a blood and lymphatic vascular supply connecting stem cells coexist with donor hematopoietic stem cells and graft and host may be a determining factor in the qualif- yield cells of the myeloid and lymphoid lineages. A donor cell infusion is the administration of donor bone marrow or hematopoietic stem cells to the recipient of a solid organ transplant to establish chimerism and donor cell acceptance. An irradiation chimera is an animal or human whose lymphoid and myeloid tissues have been destroyed by lethal irradiation and successfully repopulated with donor bone marrow cells that are genetically different. It is the administration of suffcient ion- izing radiation over the whole body to destroy hematopoietic cells in the bone marrow. Radiation bone marrow chimeras: Mice that have been Unvascularized subjected to heavy radiation and then reconstituted with allo- geneic bone marrow cells, i. Allogeneic (or allogenic) is an adjective that describes genetic variations or differences among members or strains of the same species. Immunologically privileged sites include (1) the ante- between genetically dissimilar humans or unrelated mem- rior chamber of the eye, (2) the substantia propria of the cor- bers of other species. Foreign grafts implanted Alloantiserum is an antiserum generated in one member or in these sites show a diminished ability to induce transplanta- strain of a species not possessing the alloantigen (e. These immunologically privileged tocompatibility antigen), with which they have been chal- sites usually fail to protect alien grafts from the immune lenged, that is derived from another member or strain of the refection mechanism in hosts previously or simultaneously same species. Allorecognition is the detection of allelic differences mani- Leptin the antiobesity hormone, is an endothelial cell mito- fested by cells of one member of the species by lymphocytes gen and chemoattractant, and it induces angiogenesis in a of another individual. The direct pathway of allorecognition is the process whereby the allogeneic effect (Figure 22. An alloreactive T cell is a T lymphocyte from one member of a species capable of responding to an allogeneic antigen Alloreactive is the recognition by antibodies or T lympho- from another member of the same species. A take is the successful grafting of skin that adheres to the recipient graft site 3 to 5 d following application. Thin grafts are more likely to “take” than thicker ences between members of the same species. It represents the grafts, but the thin graft must contain some dermis to be suc- immune response to an alloantigen based on recognition of cessful. Allogeneic disease includes the pathologic consequences of Engraftment is the phase during which transplanted bone immune reactivity of bone marrow allotransplants in immu- marrow manufactures new blood cells. The rejection is based upon both cell-mediated and antibody-mediated immu- Alloimmunization is defned as an immune response pro- nity against cells of the graft by the histoincompatible reci- voked in one member or strain of a species with an alloantigen pient. First-set rejection usually occurs within 2 weeks after derived from a different member or strain of the same species. The placement of a second graft with the Examples include the immune response in man following same antigenic specifcity as the frst in the same host leads Transplantation Immunology 689 Immunological rejection is the destruction of an allograft or even a xenograft in a recipient host whose immune system has been activated to respond to the foreign tissue antigens. Rejection is an immune response to an organ allograft such as a kidney transplant. Hyperacute rejection is due to pre- formed antibodies and is apparent within minutes following transplantation. Antibodies reacting with endothelial cells cause complement to be fxed, which attracts polymorpho- nuclear neutrophils, resulting in denuding of the endothelial lining of the vascular walls. This causes platelets and fbrin plugs to block the blood fow to the transplanted organ, which becomes cyanotic and must be removed. Acute rejection occurs within days to weeks follow- First set ing transplantation and is characterized by extensive cellular infltration of the interstitium. These cells are largely mono- 7 to 8 days nuclear cells and include plasma cells, lymphocytes, immu- Second set noblasts, and macrophages, as well as some neutrophils. This demonstrates the presence of immunological memory Second-set rejection is rejection of an organ or tissue graft learned from the frst experience with the histocompatibility by a host who is already immune to the histocompatibility antigens of the graft. When the donor and recipient differ only antigens of the graft as a consequence of rejection of a previ- at minor histocompatibility loci, rejection of the transplanted ous transplant of the same antigenic specifcity as the second, tissue may be delayed, depending upon the relative strength of or as a consequence of immunization against antigens of the the minor loci in which they differ. The accelerated second-set rejection compared immune individual, such as those with preformed antibodies, to rejection of a frst graft is reminiscent of a classic second- may undergo hyperacute or accelerated rejection. The accelerated rejection polymorphonuclear neutrophil attraction, and denuding of is seen when regrafting is performed within 12 to 80 d after the vessel wall, followed by platelet accumulation and fbrin rejection of the frst graft. As the blood supply to the organ is interrupted, the due to sensitization of the recipient by the frst graft. Hyperimmunized individual: A person who has formed Immunofuorescent “staining” of C4d in peritubular cap- alloantibodies against an antigen to which the subject was pre- illaries of renal allograft biopsies reveals a humoral compo- viously exposed, such as a prior allograft, blood transfusion, nent of rejection (Figure 22. May sometimes be attributable to natural anti- bodies specifc for antigenic determinants of pathogens but First-set rejection is an acute form of allograft rejection in which cross-react with allogeneic donor antigens of a graft. White graft rejection is an accelerated rejection of a sec- Lymphocyte immune globulin (injection): Indicated in ond skin graft performed within 7 to 12 d after rejection of renal transplantation for the management of allograft rejec- the frst graft. It is characterized by lack of vascularization tion in renal allotransplant recipients. The charac- with conventional therapy at the time of rejection, it increases teristic changes are seen by day 5 after the second grafting the frequency of resolution of the acute rejection episode. The transplanted tissue is rendered white because May be used also in conjunction with other immunosuppres- of hyperacute rejection, such as a skin or kidney allograft. Preformed antibodies occlude arteries following surgical Indicated also in aplastic anemia for the treatment of mod- anastomosis, producing infarction of the tissue graft. Antibodies present induce falsely elevated results in immunoassays that involve in this antiserum combine with T cells and other lympho- mouse antibodies. This may represent a problem in organ cytes in the circulation to induce immunosuppression. Rarely, recirculating T lymphocytes are removed in patients experiencing rejection crisis by thoracic duct drainage or extracorporeal irradiation of the blood. The allograft was removed within a few humoral and cell-mediated immune response of a recipient hours following transplantation.
Newly synthesized immunoglobulin molecules for a heterologous epitope than for the homologous one that have different properties based on their immunoglobulin class stimulated its synthesis generic 250 mg zithromax fast delivery infection 2 bio war simulation. Nevertheless purchase 250mg zithromax with amex antibiotics for dogs ear infection uk, antigen-binding specifcities reside in the Fab regions of antibody molecules, which governs their Heterocytotropic antibody is an antibody that has a greater interactions with antigens in vitro and in vivo. By contrast, affnity when fxed to mast cells of a species other than the complement binding and activation capabilities, binding to cell one in which the antibody is produced. Frequently assayed by surface, and transport through cells reside in the Fc region of skin-fxing ability, as revealed through the passive cutaneous the molecule. Interaction with the antigen for which these fers according to the immunoglobulin class, each with its own “fxed” antibodies are specifc may lead to local heterocy- characteristic half-life. Some antibodies are protec- tive, others cross the placenta from mother to fetus, whereas Heterogenetic antibody: See heterophile antibody. Antibodies are a diverse and Heterophile antibody is an antibody found in an animal of unique category of proteins whose antigen-binding diversity one species that can react with erythrocytes of a different is expressed in the 1020 antibody molecules synthesized from and phylogenetically unrelated species. Heterophile antibodies are detected in infectious mononucleosis patients who demonstrate antibodies reactive Antibodies are glycoprotein substances produced by B with sheep erythrocytes. To differentiate this condition from lymphoid lineage cells, termed plasma cells, in response serum sickness, which also is associated with a high titer of to stimulation with an immunogen. They possess the abil- heterophile antibodies, the serum sample is absorbed with ity to react in vitro and in vivo specifcally and selectively beef erythrocytes which contain Forssmann antigen. This with the antigenic determinants or epitopes eliciting their treatment removes the heterophile antibody reactivity from production or with an antigenic determinant closely related the serum of infectious mononucleosis patients. Antibodies in the blood serum of any given animal species Homocytotrophic antibody is an antibody that attaches bet- may be grouped according to their physicochemical prop- ter to animal cells of the same species in which it is produced erties and antigenic characteristics. The term not restricted to the plasma but may be found in other body usually refers to an antibody that becomes fxed to mast cells 233 234 Atlas of Immunology, Third Edition of an animal of the same species, which results in anaphylaxis least negative charge. Originally, globulins were character- with the release of pharmacological mediators of immediate ized based on their insolubility in water, i. These include histamines and other vasoac- lins, or sparing solubility in water, i. Anti-allotypic antibodies are antibodies specifc for allo- topes of an immunoglobulin molecule derived from a member γ globulin is an obsolete designation for immunoglobulin. These serum proteins show the lowest mobility toward thev anode during electrophoresis when the pH is neutral. The γ Anti-isotypic antibodies are antibodies generated in one spe- globulin fraction contains immunoglobulins. It is the most cat- cies specifc for antigenic determinants found only on one ionic of the serum globulins. Polyclonal antibodies are multiple immunoglobulins respond- Antibody-binding site is the antigen-binding site of an anti- ing to different epitopes on an antigen molecule. This multiple body molecule, known as a paratope, which is comprised of stimulation leads to the expansion of several antibody-forming heavy chain and light chain variable regions. The paratope clones whose products represent a mixture of immunoglobu- represents the site of attachment of an epitope to the antibody lins in contrast to proliferation of a single clone which would molecule. The complementarity-determining hypervariable yield a homogeneous monoclonal antibody product. Thus, regions play a signifcant role in dictating the combining site polyclonal antibodies represent the natural consequence of structure together with the participation of framework region an immune response in contrast to monoclonal antibodies, residues. The T cell receptor also has an antigen-binding site which occur in vivo in pathologic conditions such as multiple in the variable regions of its α and β (or γ and δ) chains. Pyroglobulins are monoclonal immunoglobulins that undergo irreversible precipitation upon heating to 56°C. Whereas most immunoglobulins are unharmed be named the immunoglobulin supergene family. These molecules share in com- jects have multiple myeloma, and the remaining half have mon with each other an immunoglobulin-like domain with a a lymphoproliferative disorder such as macroglobulinemia, length of approximately 100-amino acid residues and a cen- carcinoma, or systemic lupus erythematosus. Their relevance tral disulfde bond that anchors and stabilizes antiparallel β to disease is unknown. Immunoglobulin superfamily members may share homology Euglobulin is a type of globulin that is insoluble in water but with constant or variable immunoglobulin domain regions. In the past, it was used to designate Various molecules of the cell surface with polypeptide chains that part of the serum proteins that could be precipitated by whose folded structures are involved in cell-to-cell interac- 33% saturated ammonium sulfate at 4°C or by 14. All three globulin fractions demonstrate anodic mobility that is less than that of albumin. Antitoxin is an antibody specifc for exotoxins produced An antiserum contains a heterogenous collection of antibodies by certain microorganisms such as the causative agents that bind the antigen used for immunization. Prior to the antibiotic era, anti- specifc structure, antigenic specifcity, and cross-reactivity con- toxins were the treatment of choice for diseases produced tributing to the heterogeneity that renders an antiserum unique. Different epitopes on the antigen Serum antitoxins are antibodies specifc for exotoxins molecule stimulate this multiplicity of antibodies. Prior to the use of antibi- Antiagglutinin is a specifc antibody that interferes with otics, antitoxins were the treatment of choice for diseases the action of an agglutinin. Antibody detection: Techniques employed to detect anti- bodies include immunoprecipitation, agglutination, com- ss plement-dependent assays, labeled antiimmunoglobulin ss reagents, blotting techniques, and immunohistochemistry. Enzyme-based immunoassays, blotting methods, and immu- nohistochemistry are routine procedures to detect antibodies and to characterize their specifcity. Antibody titer is the amount or level of circulating anti- such as those from Corynebacterium diphtheriae and body in a patient with an infectious disease. Two separate titer determinations are required to refect ties that an individual can synthesize. Amboceptor (historical): Paul Ehrlich (circa 1900) con- Antitoxin assay (historical): Antitoxins are assayed bio- sidered antisheep red blood cell antibodies, known as logically by their capacity to neutralize homologous toxins amboceptors, to have one receptor for sheep erythrocytes as demonstrated by production of no toxic manifestations fol- and another receptor for complement. The term gained lowing inoculation of the mixture into experimental animals, worldwide acceptance with the popularity of complement e. They may be tested serologically by their fxation tests for syphilis, such as the Wasserman reaction. Although incapable of leading to pre- Humoral immunity is immunity attributable to specifc cipitation or agglutination, univalent antibodies or Fab frag- immunoglobulin antibody and present in the blood plasma, ments resulting from papain digestion of an IgG molecule lymph, other body fuids, or tissues. The antibody may also might block precipitation of antigen by a typical bivalent adhere to cells in the form of cytophilic antibody. Antibodies that are the messengers of humoral Antitoxin unit: A unit of antitoxin is that amount of anti- immunity are derived from B cells. For purposes of discus- toxin present in 1/6000 g of a certain dried unconcentrated sion, it is separated from so-called cellular or T cell-mediated horse serum antitoxin which has been maintained since 1905 immunity, though the two cannot be clearly distinguished at the National Institutes of Health in Bethesda, Maryland. Antigen binding sites Both the American and international units of antitoxin are Heavy chainHeavy chain the same. PlasmaPlasma membranemembrane AntibodyAntibody B-cell antigenB-cell antigen An antigen-binding site is the location on an antibody mol- (secreted)(secreted) receptorreceptor ecule where an antigenic determinant or epitope combines (membrane bound)(membrane bound) with it. The antigen-binding site is located in a cleft bordered by the N-terminal variable regions of heavy and light chain figure 7.