xid mice fail to express an anti-dextran immune response but carry alpha(1-3)dextran-specific lymphocytes in their potential repertoire.

Even after repeated immunizations with alpha(1-3)dextran (Dex) male (CBA/N x BALB/c)F1 mice fail to produce specific antibodies whereas nondefective female littermates express an idiotype-positive anti-Dex immune response. This failure of xid mice to express serum anti-Dex immunoglobulins is not only limited to immunization with the thymus-independent (TI-2) antigen Dex, since immunization with anti-idiotypic antibodies against Dex-specific idiotypes does not overcome this defect. When xid lymphocytes are cultured in the presence of mitogens, in vitro anti-Dex responses are markedly reduced. We show here that alpha(1-3)Dex-specific hybridomas can be established by fusion of splenic lymphocytes from xid mice to Sp2/0 myeloma cells. Therefore, these mice do carry the potential to generate B cells specific for Dex. All hybridoma antibodies were found to be of IgM isotype, bearing the lambda light chain typical for alpha(1-3)Dex-specific antibodies. Whereas monoclonal anti-Dex antibodies obtained from spleen cell hybridomas from female littermates showed variable idiotope patterns, hybridoma proteins from the immune-defective NBF1-xid mouse expressed only a limited pattern of Dex-specific idiotopes, suggesting that these hybridomas derived from a common precursor.