Heterogeneity in the specificities of an alloreactive T helper cell line

Heterogeneity in antigen recognition of an alloreactive helper T-cell line was studied by repeated limiting dilution cloning. Analysis of the fine specificities of these clones showed that the gain of reactivity to new antigens by the T-cell line included the generation of non-cross-reactive T cells specific to new major histocompatibility (MHC) antigens. Analysis of function revealed that all the T-cell clones studied had similar cell surface antigens and secreted interleukin 4 (IL-4) and IL-5/IL-3 but not IL-2 or gamma interferon (IFN-gamma). The T-cell clones served as helper cells for B cells expressing the appropriate MHC antigens to both clonal proliferation and differentiation into antibody-producing cells.