FREQUENT EXPRESSION OF INTERLEUKIN-9 MESSENGER-RNA AND INFREQUENT INVOLVEMENT OF INTERLEUKIN-9 IN PROLIFERATION OF PRIMARY ADULT T-CELL LEUKEMIA-CELLS AND HTLV-I INFECTED T-CELL LINES

To examine the possibility that interleukin-9 (IL-9) may be involved i n oncogenesis and the proliferation of adult T-cell leukemia (ATL) cel ls, we examined the expression of IL-9 mRNA and growth response to IL- 9 in five human T-lymphotropic virus type-I (HTLV-I) infected T-cell l ines and in primary leukemia cells in peripheral blood from eight pati ents with ATL (four acute ATL and four chronic). Four out of five cell lines expressed IL-9 mRNA not correlated with Tax expression. Primary ATL cells from all patients also expressed IL-9 mRNA not correlated w ith the clinical forms. Recombinant IL-9 showed growth enhancing activ ity in only one out of five cell lines and one out of eight patients' primary leukemic cells, These results suggest the infrequent involveme nt of IL-9 in the proliferation of ATL cells, both primary tumor cells and HTLV-I infected T-cell lines. (C) 1997 Elsevier Science Ltd. All rights reserved.