Selective reconstitution of nude mice with long-term cultured and cloned specific helper T cells.

An antibody response is the end result of complex interactions among T cells, adherent cells and B cells. An understanding of the interactions involved has proved difficult as pure populations of these cells have not been available. By making use of T-cell growth factor, we were able to grow normal helper T cells specific for heterologous erythrocytes. Because specificity and mechanism of action of these cells had been demonstrated solely in culture, we sought to establish their competence in the whole animal. We have therefore examined here whether antigen-specific helper T cells, maintained in culture over long periods, would enable syngeneic nude mice to respond to T-cell dependent antigens. The results show that specific helper T cells, propagated in serum-free medium in vitro for up to 15 months, can selectively and specifically reconstitute syngeneic C57BL/6J nu/nu mice. Depending on the specificity of the injected helper T cells, such nude mice could respond to sheep red blood cells (SRC) but not to horse red blood cells (HRC) and vice versa. The magnitude of the response was comparable to that of normal mice and could exceed it by almost 10-fold, depending on the source and number of injected helper T cells.