Expression of the interleukin 6 gene in acute myeloid leukemia and myelodysplastic syndromes: a report on 49 cases.

We studied the expression of IL 6 gene in 49 patients, including 21 chronic myelomonocytic leukemias (CML), 9 other myelodysplastic syndromes (MDS), 18 acute myeloid leukemias (11 M2 or M3 and 7 M4 or M5) and 1 case of acute biphenotypic lymphoid monocytic leukemia. IL 6 was found expressed only in the latter patient and in one patient with M5 acute myeloid leukemia. DNA analysis by Southern blot revealed no rearrangement in these 2 patients and in 10 of the other patients who showed no IL 6 expression. These results do not support an autocrine role for IL 6 in CMML or in other MDS. In acute myeloid leukemias, if expressed by leukemic cells, IL 6 seems to be restricted to cases with a monocytic component, although the number of patients was too small to draw any definite conclusion.