Role of interleukin-2 in depressed T-cell mitogenesis after allogeneic marrow transplantation in man.

Abstract Proliferative responses of mononuclear cells in liquid cultures to phytohemagglutinin, a T-cell mitogen, are depressed for a long time after allogeneic marrow transplantation. We examined the role of interleukin-2, a lymphokine important in T-cell mitogenesis, in the impaired phytohemagglutinin responses early after marrow transplantation. We found that interleukin-2 production, upon optimal stimulation, was impaired for mononuclear cells of most recipients early after marrow transplant. Further, we found that exogenous interleukin-2 did not restore depressed phytohemagglutinin responses of marrow transplant recipient mononuclear cells to normal. We hypothesize that early after allogeneic marrow transplant the helper T-cell pool is defective both in numbers, as shown by previous phenotypic studies, and in functional capabilities. There appear to be defects in both interleukin-2 production and interleukin-2 responsiveness in this system early after marrow transplant.