Macrophage-T cell interaction is essential for the induction of p75 interleukin 2 (IL-2) receptor and IL-2 responsiveness in human CD4+ T cells.

Fresh human CD8+ T cells showed a strong proliferative response to a high concentration of interleukin 2 (IL-2) in the absence of macrophages. In contrast, CD4+ T cells revealed no significant IL-2 responsiveness in the absence of macrophages. However, if CD4+ T cells were cocultured with macrophages, they showed higher proliferative response to IL-2 than CD8+ T cells. In accordance with the magnitude of IL-2 responsiveness, freshly isolated CD8+ T cells expressed significant amounts of p75 IL-2 receptor, while fresh CD4+ T cells did not express p75 IL-2 receptor. The expression of p75 IL-2 receptor on CD4+ T cells was induced by coculture with macrophages. The macrophage-induced p75 IL-2 receptor acquisition was blocked by monoclonal antibody (mAb) against class II antigen. Moreover, the addition of anti-CD4 mAb or anti-class II mAb to the culture caused a great inhibition of IL-2 responsiveness of CD4+ T cells. These results strongly suggest that macrophage-T cell interaction through CD4 and/or class II molecules is essential for the expression of p75 IL-2 receptor and IL-2 responsiveness in human CD4+, but not CD8+ T cells.

interleukin 2

monoclonal antibody

peripheral blood mononuclear cells