INVOLVEMENT OF INTERLEUKIN-2 IN IMMUNOLOGICAL RECONSTITUTION FOLLOWING BONE-MARROW TRANSPLANTATION IN MICE

Allogeneic or autologous bone marrow transplantation (BMT) is a curati ve form of treatment for patients with a variety of hematologic disord ers, Impaired immune reconstitution following BMT may seriously impede successful outcome, In this study, the immune function of spleen and thymus was investigated in mice exposed to myeloablative total-body ir radiation followed by syngeneic BMT, The T cell mitogen-induced prolif eration of both splenic and thymic cells was delayed, Spleen cells sta rted to respond only after 21 days, whereas thymic cells remained unre sponsive, Kinetic analysis of surface markers revealed the early appea rance of spleen cells with the CD3(+)CD4(-)CD8(-) phenotype, and the t hymus, despite a low total number of cells, displayed fast recovery of CD3(+)CD4(+)CD8(+), At the level of mRNA, a mild decrease in interleu kin-2 (IL-2) induction following phytohemagglutinin activation of sple en cells correlated with a decrease in IL-2 secretion for only the fir st 2 weeks following transplantation. The early restoration of IL-2 im plies other avenues for investigation of the immune dysfunction and it s correction following syngeneic BMT.