Allospecific human T cell lines and clones which mediate HLA-DR restricted helper activity

In order to analyze the immunoregulatory activity of allospecific human T cells, we have combined the techniques of limiting dilution culture and IL-2 dependent T cell growth to generate cloned alloreactive T cell lines (TCL). These TCL have been expanded in continuous culture for greater than 8 mo with retention of stable phenotypic and functional characteristics. For example, phenotypic analysis of alloproliferative TCL, utilizing a panel of monoclonal antibodies, demonstrate that these cultures are comprised of T cells belonging exclusively to the T3+ T4+ T8- "helper" or "inducer" T cell subset. Coculture of cloned alloproliferative TCL cells with a panel of allogeneic stimulators reveals that these clones are specifically reactive against the HLA-DRw1 determinant. Of greater interest, coculture of selected alloproliferative TCL cells with DRw1+ but not DRw1- B cells results in a vigorous polyclonal response as measured by the reverse hemolytic plaque assay. Although major histocompatibility complex restriction of this T-B interaction operates at the inductive level, help is at least partially unrestricted at the effector level as alloantigen-activated TCL cells provide demonstrable, although not maximal, help for DRw1- B cells.