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Complexing a human IgG lambda paraprotein with a monoclonal antibody (McAb) to a lambda-chain determinant markedly depressed the anti-lambda response of immunized mice. No anti-lambda was found in the serum after two or four injections of the complex, whereas high titres of anti-lambda chain antibody were found in the sera of mice immunized with the IgG paraprotein complexed with any single anti-gamma chain McAb or with a pool of anti-gamma chain McAbs. Responses to the highly immunogenic Fc gamma portion of the molecule were not suppressed by complexing with a single anti-gamma chain McAb and were only slightly suppressed after complexing with a pool of anti-gamma chain McAbs. Some anti-Fc gamma antibody was produced by all animals receiving a single injection of the immunogen complexed to any McAb, but free immunogen did not generate a primary response. Complexing the IgG with an anti-Fc gamma McAb enhanced the response to to the poorly immunogenic C gamma 1 domain but no anti-C-gamma 1 was produced by mice receiving the IgG complexed with an anti-C-gamma 1 McAb. In immunizations with 'free' (Bence-Jones) lambda chain, all the antibody produced was directed against 'free'-specific determinants. Complexing the Bence-Jones protein with McAbs to 'free' or 'general' determinants on the lambda chain did not enhance or suppress the response. It is concluded that the response to weakly or moderately immunogenic, but not to strongly immunogenic, regions of the molecule may be suppressed by complexing the immunogen with a McAb of appropriate specificity. Possible reasons for this result are discussed.

Individual specific antisera were raised against the monoclonal serum component from six IgG myeloma patients. Idiotypic (Id) determinants were identified in direct or indirect immunofluorescence (IFL) on 0.5-44% B lymphocytes from five patients with active disease. Id determinants were not detected on B lymphocytes from one IgG-k myeloma patient with an imbalance in the expression of upsilon heavy chains and kappa light chains. Nor were Id determinants detected on E-rosetting cells. Id structures were usually present together with upsilon chains on monoclonal B lymphocytes, some of which also carried mu and/or delta chains. Blood cells with lymphoplasmacytoid appearance were abundant in two patients. These cells carried IgG with Id determinants both in the cytoplasm and on the surface. Fc receptors were present on most cells carrying surface Id structures but were rare on cells with cytoplasmic monoclonal characteristics. The results further support the hypothesis of multiple myeloma as a differentiating B-lymphocyte tumour.

In ragweed-sensitive and ragweed non-sensitive subjects the proportions of T lymphocytes bearing receptors for the Fc portion of IgG (T gamma) and IgM (T mu) were examined as obtained from the blood, and after treatment in vitro with ragweed antigen E or concanavalin-A. The proportion of T gamma and T mu cells, from the peripheral blood of ragweed-sensitive and ragweed non-sensitive persons, untreated in vitro, were not statistically different. However, when T cells from ragweed-sensitive subjects were exposed to ragweed antigen E, the T mu subpopulation was significantly increased (P less than 0.001) without change in the T gamma population. The reverse change occurred when cells of ragweed non-sensitive subjects were treated with antigen E; there was an increase in the T gamma subpopulation (P = 0.01) but no change in number of the T mu cells. Cells from both the sensitive and non-sensitive groups showed increase in number of T gamma and reduced numbers of T mu cells when incubated with concanavalin A. Since T gamma and T mu cells appear to have a regulatory function on B lymphocyte differentiation and antibody production, the pattern of responses of T gamma and T mu subpopulations in vitro to antigen E in ragweed-sensitive and ragweed non-sensitive subjects may reflect a difference in the cellular control of the immune response to ragweed antigen E.

T-, B- and Fc-gamma-receptor-bearing lymphocytes were detected using six different membrane markers in patients suffering from asthma having either normal or low serum IgA levels. E rosettes, aE rosettes and a human anti-T lymphocyte antiserum (HTLA) were used for T cell determination. In patients with low serum IgA levels E rosettes were significantly decreased. B lymphocytes were identified by EAC rosette formation and visualization of surface membrane immunoglobulins (SmIg). No significant difference was seen. Fc-gamma-receptor-bearing lymphocytes were assessed by the EA rosette assay and were significantly decreased in asthmatics with normal IgA levels. This result might be explained by the presence of immune complexes.

A survey for constant region gamma-chain allotypes (de locus) was undertaken in different lagomorph genera. As yet only Pronolagus rupestris, a paleolaginae, showed the presence of a determinant similar to rabbit d12 although it lacked the widespread e15 determinant. All seven individuals possessed the d12 like determinant which was studied by immunodiffusion, haemagglutination inhibition, radiobinding and binding inhibition assays. In addition, a new enzymic method for typing for d12, based on the presence of the asymmetric rabbit hinge carbohydrate linked to the d12 characteristic threonine, is presented. This method suggests, however, that, unlike the d12 rabbit, Pronolagus does not seem to have a majority of IgG molecules with a glycosylated hinge.