Functional properties of T cell clones with a double specificity for alloantigens and foreign antigens.

Four keyhole limpet hemocyanin (KLH)-specific clones prepared from the lymph node of CB6F1 mice immunized with KLH had a proliferative response restricted to parental major histocompatibility complex (MHC)-encoded antigens. These clones provided help for CB6F1 trinitrophenyl-ovalbumin (TNP-OVA)-primed B cells to mount IgM and IgG plaque-forming cell (PFC) responses in the presence of KLH-TNP conjugate. In addition, two of these clones (A12.11 and F6) proliferated in response to allogeneic cells from mice strains bearing H-2k or H-2q haplotypes, respectively. However, they did not provide help for C3H/He or B10.Q primed B cells. The clonal nature of A12.11 and F6 was demonstrated by subcloning and in BUdR-suicide experiments. The proliferative response to KLH was ablated by anti-Iad antibodies, whereas the proliferation induced by C3H/HeJ stimulating cells was ablated by anti-Iak antibodies. Furthermore, both responses were inhibited by a monoclonal anti-clonotype (idiotype) antibody. Taken together, these results strongly support the hypothesis that the same receptor recognizes alloantigens and KLH associated with self-antigens.