title: Physiology of IgD. I. Compensatory phenomena in B lymphocyte activation in mice treated with anti-IgD antibodies.
abstract: The role of delta-positive cells in the immune response was studied by comparing the effects of treatment with allotype-specific IgD hybridoma antibody on homozygous BALB/c or SJL/J and heterozygous (BALB x SJL)F1 mice. Homozygous mice, injected from birth with the relevant anti-delta antibody, made primary or secondary immune responses to intravenously injected trinitrophenyl (TNP)-Brucella abortus, TNP-Ficoll, and TNP-keyhole limpet hemocyanin, which did not differ significantly from those of control mice, despite the fact that IgD+ cells were depleted and Ig+ cells were markedly reduced in the spleens of treated mice. Responses in nodes draining a local injection of TNP-Brucella abortus were, however, significantly suppressed. Heterozygous mice, injected from birth with either anti-Ig-5a or anti-Ig-5b, showed a marked reduction in the number cells producing IgG antibody of linked allotype specificity in the secondary response to intravenously injected sheep erythrocytes. A corresponding decrease in the amount of serum IgG2a of that allotype specificity was also noted. However, in agreement with the results obtained in homozygotes, heterozygotes injected simultaneously with anti-IgD directed against each of the allotypes made normal, if not enhanced, plaque-forming cell responses of both allotype specificities. Similarly, serum IgG2a levels were normal in all but one mouse treated in this fashion. These results indicate that IgD+ cells are not essential for an immune response in vivo. Although the delta-positive cell is used preferentially under normal conditions, it appears that an alternative mechanism exists by which, in the absence of these cells, the animal is able to make a normal immune response.
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000502:physiology*; D000917:Antibody Formation; D001402:B-Lymphocytes / Q000276:immunology*; D006579:Heterozygote; D007108:Immune Tolerance; D007072:Immunoglobulin D / Q000276:immunology* / Q000502:physiology*; D008213:Lymphocyte Activation; D051379:Mice / Q000235:genetics
chemical_list: D000888:Antibodies, Anti-Idiotypic; D007072:Immunoglobulin D