CHARACTERIZATION AND REGULATION OF INTERLEUKIN-4 RECEPTOR IN ADULT T-CELL LEUKEMIA-CELLS

We studied the expression of the receptor of interleukin (IL)-4, one o f the T cell growth factors, on fresh peripheral blood leukemic cells from adult T-cell leukemia (ATL) patients. Flow cytofluorometric analy sis with a monoclonal antibody to the IL-4 receptor (IL-4R) were used to investigate whether expression of IL-4R on ATL cells is different f rom that on normal lymphocytes and other types of leukemic cells. Leuk emic cells from acute type ATL patients synthesize IL-4R without stimu lation, at levels much higher than normal resting lymphocytes and othe r types of leukemic cells. Furthermore, leukemic cells from acute type ATL showed higher IL-4R expression than that of chronic type ATL or h uman T-cell leukemia virus type I carriers. In addition, there was cor relation between expression of IL-4R on the cell surface and the proli ferative response to IL-4. Both IL-4 and IL-2 induced upregulation of IL-4R on activated normal T cells but not on ATL cells. These results suggest that abnormal expression of IL-4R may display different biolog ical activities in ATL compared with other types of leukemia. Furtherm ore, the high expression of IL-4R in ATL may be involved in the prolif eration of leukemic cells and the leukemogenesis in this disease.