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The immunizing ability of immune complexes preformed between EA and EA-hyperimmune serum was investigated in adult rats. After immunization with complexes at equivalence, the pattern of suppressed IgE responsiveness was similar to that induced when a small volume of immune serum accompanied routine immunization. We have suggested that the underlying principle is the same, and that the IgE response can be regulated by immune complexes. The ability to influence an ongoing IgE response was determined by treating with complexes at various times after immunization. While the primary IgE levels were differentially affected, the most consistent suppression was seen at the secondary stage. The data suggest that a stage of B-cell differentiation has been interrupted and that IgE antibody-producing cells have been prevented from developing. [ABSTRACT FROM AUTHOR]

In order to test the relative immune competence of a minor VH subgroup (y), the concentrations of rabbit Ig bearing the VH subgroups a and y were determined in experimentally immunized rabbits. Three groups of three rabbits each were immunized with either Micrococcus luteus, bovine serum albumin or an alloantigenic determinant (b4) of the rabbit κ light chain. The ratios of VHY to VHa Ig in the pre-immune sera ranged from 1:8 to 1:283. In five of the nine rabbits, the VHy to VHa ratios in affinity purified antibody (Ab) closely reflected the ratios of VHy to VHa in pre-immune serum. Of the remaining four rabbits, three produced disproportionately low amounts of VHy Ab, when compared to pre-immune values, while one rabbit produced virtually no VHY Ab. Regardless of the levels of VHY and VHa Ab detected, the kinetics of Ab production by each subgroup during the course of the immune response were similar to each other. When total serum levels of the subgroups were analysed, all rabbits displayed increases (6-45O%) in total serum levels of both VHa Ig and total IgG following immunization, while in eight out of nine rabbits the level of VHy Ig remained unchanged. Our observations suggest that the immune repertoire of the minor VHy subgroup is sufficiently diverse to generate VH regions which react with a variety of antigens, and in five out of nine rabbits, VHY Ab-producing clones compete well with VHa Ab-producing clones. In addition, it appears that clones of the major and minor VH subgroups, once triggered, are under similar regulatory controls with respect to specific Ab, but differ with respect to non-specific Ig production. [ABSTRACT FROM AUTHOR]

Different immunoglobulin preparations of human monoclonal IgM, normal human and rat IgG, as well as purified rabbit antibodies were treated by various methods, fragmentation, aggregation and complexing with antigen. The ability of the treated and untreated preparations to fix isolated human CT, to activate the classical complement pathway (to consume C4 in normal human serum) were compared. It was found that the different methods affected the conformation of the immunoglobulin molecules in different ways and induced changes to a greater or lesser extent in the two capacities of the preparations tested. In the case of the monoclonal IgM preparation a strong CT-fixation was observed without measurable complement activation. Other preparations, interfacially aggregated human IgG, BSA-anti-BSA and OA-anti-OA immune complexes had a very weak CT-fixing but a marked complement activating capacity. Some preparations, e.g. heat-aggregated IgG, both fixed and activated C1 effectively, aggregates with a complement-activating capacity without C1-fixing effect were separated by gel-filtration. It was demonstrated further, that at a given time only a part of the activated C1 molecules could be found fixed to the immunoglobulins, the other part was released into the fluid phase after activation. On the basis of the results of this and previous studies a hypothesis is proposed suggesting three possible results of the interaction between C1 and the different preparations: (1) firm fixation and activation; (2) binding not followed by activation and (3) a transient binding leading to activation. The possible application of this hypothesis for the interpretation of the results of the different methods for detecting immune complexes is discussed. [ABSTRACT FROM AUTHOR]

A quantitative method for determining specific antibody in the different classes of immunoglobulins is described. The technique is based on the binding of all antibody present in an immune serum with antigen, and the sub- sequent precipitation of the bound immunoglobulins with a heterologous antiserum specific for the antigen employed. The concentration of each immunoglobulin class is determined by means of single radial immunodiffusion, before and after removal of its antibody-active portion. The accuracy of the measurements is essentially that of the immunodiffusion technique, and the whole analysis, applied to four immunoglobulin classes, requires only 0·06 ml of serum. The applicability of the technique has been tested using sera from mice immunized with ferritin by different routes. Antibody activity was predominant in the IgG1 and IgG2 immunoglobulin classes. However, measurable anti-ferritin activity in the IgM and IgA classes was also found in a limited number of sera. [ABSTRACT FROM AUTHOR]

Rabbit and chicken anti-human thrombocyte sera absorbed exhaustively with human plasma, fibrinogen, erythrocytes, leucocytes and liver powder, were used for the investigation of organ specific antigens of human thrombocytes. The absorbed chicken anti-human thrombocyte serum revealed a very high agglutinating and fluorescence activity, which aided the characterization of two different types of organ-specific antigens of thrombocytes; antigens common to human and animal platelets, and antigens specific for human platelets only. The two types of antigens were found in all platelet fractions examined, the membrane, granule and soluble fractions. [ABSTRACT FROM AUTHOR]

Slowly sedimenting components with a sedimentation velocity of about 7S and reacting with specific antisera against IgM were found in six pathological human sera. Four of these came from patients with different forms of reactive macroglobulinaemia of infectious origin. Similar components were produced from purified IgM preparations by bacterial action, and to a lesser extent by spontaneous splitting at room temperature. The conditions for such a splitting were, however, absent for most of the sera investigated in this study. The possibility that slowly sedimenting IgM-like components are artefacts, is discussed. [ABSTRACT FROM AUTHOR]

Antisera to specific proteins in herpes simplex infected cells were produced by immunization of rabbits with infected rabbit kidney cells. These antisera were highly virus specific and produced up to twelve lines in immunodiffusion tests against infected cell extracts. Acrylamide electrophoresis and immunoelectrophoresis revealed up to ten virus specific proteins of varying size. [ABSTRACT FROM AUTHOR]

Canine precipitating and non-precipitating antisera against bovine serum albumin where studied by quantitative isotope precipitin and coprecipitation techniques. Canine precipitating antisera yielded curves of incomplete precipitation of antigen in antibody excess. Non-precipitating canine antibody can inhibit precipitation of antigen by rabbit precipitating antibody under certain conditions. Canine precipitating antibody contains a &gamma-globulin fraction which results in complete precipitation of antigen in antibody excess. It is suggested that canine non-precipitating antibody is a faster moving globulin which is present in canine precipitating antisera and the combined effect of canine non precipitating and precipitating antibodies results in the characteristic types of canine precipitin curve. [ABSTRACT FROM AUTHOR]

Dissociation rate measurements were determined on antisera following single and multiple intravenous injections of antigen and after injection of antigen incorporated into adjuvant. It was found that regardless of the amount, route, or number of injections the dissociation characteristics of all sera were similar, reaching the same maximum binding strength within the same time period following immunization. The relative production of 19S and 7S antibody was studied and it was found: (a) insufficient 19S antibody is formed to account for the change in dissociation characteristics that occur following immunization; (b) at the same stage of immunization, 19S and 7S antibody have similar rates of dissociation from antigen, but 19S antibody combines more slowly with antigen than 7S antibody; (c) the haemagglutination technique show's no correlation with binding or precipitin methods when estimates as to the relative amounts of 19S and 7S antibody present in sera are made. [ABSTRACT FROM AUTHOR]

An in vitro assay procedure for evaluating the antibody response to glomerular basement membranes, lung basement membranes and tendon fibrils indicated a sharing of identical or similar antigenic components. At least 70 per cent of the glomerular basement membrane-binding antibodies are absorbable by tendon fibrils, and eluates from such tendon preparations are not nephrotoxic. Within the species employed (man, rabbit and dog) for glomerular basement membrane sources, there appears to be no species specificity as regards the presence of the nephrotoxic component. Immunization of sheep with either canine or rabbit glomerular basement membrane leads to the elaboration of a haemagglutinin for the respective species. [ABSTRACT FROM AUTHOR]