SECRETION OF IL-2, IL-3, IL-4, IL-6 AND GM-CSF BY CD4-ALPHA-BETA+ T-CELL CLONES DERIVED EARLY AFTER ALLOGENEIC BONE-MARROW TRANSPLANTATION(AND CD8+ TCR)

Secretion of different cytokines may be an important T-cell effector m echanism for bone marrow engraftment, graft versus host disease and gr aft versus leukaemia effects after allogeneic bone marrow transplantat ion (BMT). Cytokine secretion and autocrine proliferative capacity of T-cell clones derived from leukaemia patients 3-6 weeks after allogene ic bone marrow transplantation were investigated. Only a minority of p ost-transplant T-cell clones (23/120; 19%) was capable of undergoing a utocrine proliferation. By contrast, 21/65 (32%) normal control clones from the marrow donors derived under the same conditions were autocri ne proliferative. All clones were interleukin-2 (IL-2) responsive. A m ajority (12/17; 71%) of autocrine proliferating post-transplant clones secreted detectable I L-2. Compared with control clones, CD4+ T-cell clones derived early after BMT produced decreased levels of interleuki n-4 (IL-4) and interleukin-6 (IL-6), whereas secretion of interleukin- 3 (IL-3) and granulocyte/macrophage colony-stimulating factor (GM-CSF) showed no significant difference. The small number (n = 8) of post-tr ansplant CD8+ clones showed decreased production of IL-3, IL-4 and IL- 6 compared with control clones, but normal secretion of GM-CSF. Neithe r CD4+ nor CD8+ T-cell clones secreted interleukin-7 (IL-7).