CELLULAR IMMUNOLOGY 82,282-29 1 (1983) Selective Suppression by Auto-Anti-idiotypic Antibody of B-Cell ldiotype Repertoires Generated after Stimulation with the Same Hapten on T-Dependent and T-Independent Carriers’ MYRON R. SZEWCZUK~ Department of Microbiology and Immunology, Queen’s University, Kingston, Ontario K7L 3Nr5 Canada Received February 14, 1983; accepted August 3, 1983 In the present study, we investigated whether auto-anti-idiotypic antibody in the immune sera from old mice could recognize antitrinitrophenyl (TNP) plaque-forming cells (PFC) generated after stimulation with the T-dependent and T-independent forms of the hapten, TNP. Young and old C57BL/6J male mice were immunized with a variety of T-dependent (TNP-bovine y- globulin, TNP-BGG; TNP-keyhole Limpet hemocyanin, TNP-IUH; ovalbumin, OVA; bovine serum albumin, BSA; BGG) and T-independent (TNP-BruceNa abortus, TNP-BA; TBP-Ficoll; TNP-polyacrylamide beads, TNP-PAA) antigens either in complete Freund’s adjuvant (CFA) or in soluble form. Splenic anti-TNP or antiprotein PFC responses were assayed for anti-idiotype- blocked, hapten- or protein-augmentable IgM, IgG and IgA PFC, l-2 weeks after immunization. It was found that I-month-old mice produced significantly a higher percentage of hapten aug- mentable (26-42%) IgM PFC response to T-independent antigens as compared with the 2-month- old mice (3-6% augmentation). Similarly, old mice produced a significantly higher percentage of hapten or protein augmentable (25-129%) IgG PFC response to T-dependent antigens as compared with the 2-month-old group (2-6% augmentation). The data support the view that age-related regulation of auto-anti-idiotypic antibody is a general phenomenon for immune responses to T-dependent and T-independent antigens. Hapten-reversible inhibition of plaque formation was used to determine whether anti-idiotypic antibody containing antisera from old mice could inhibit B-cell idiotype repertoires generated after stimulation with the same hapten, TNP, on T-dependent and T-independent carriers. Pools of immune sera from I-month-old mice primed with T-dependent TNP-BGG or TNP-IUH antigens but not with T-independent TNP-PAA or TNP-BA antigens, or with the proteins OVA, BSA, or BGG selectively inhibited IgM, IgG, and IgA anti-TNP PFC from 2-month-old mice that were previously primed with either TNP-BGG or TNP-IUH. In contrast, immune sera from old mice primed with TNP on either T-dependent or T-independent carriers inhibited anti-TNP PFC from mice primed with T-independent TNP-PAA or TNP-BA antigens. Immune sera from old mice primed with OVA or BSA only inhibited the respective antiprotein PFC. The immune sera from young mice did not show any appreciable inhibition of PFC generated after stimulation by any of the antigens studied. Thus, the results suggest that anti-idiotypic antibody recognition of the idiotype generated after stimulation with the T-dependent form of a hapten may be different from the recognition of that idiotype generated after stimulation with the T-independent form of the same hapten. ’ This work was supported in part by grants-in-aid of research from the Muscular Dystrophy Association of Canada, Medical Research Council of Canada MA-7347, and Gerontology Research Council of Ontario. * Gerontology Research Council of Ontario Scholar. 282 0008-8749/83 $3.00 Copyright 0 1983 by Academic Press, Inc. All rights of reproduction in any form reserved