Characterization of a leukemia-derived transforming growth factor.

A novel transforming growth factor activity has been identified in the serum-free medium derived from cultures of SMS-SB cells, a human pre-B acute lymphoblastic leukemia cell line. This activity (leukemia-derived transforming growth factor) was biochemically distinct from known fibroblast mitogens such as epidermal growth factor, transforming growth factor alpha, transforming growth factor beta, platelet-derived growth factor, and the endothelial cell growth factor/fibroblast growth factor family of mitogens. Leukemia-derived transforming growth factor was heterogeneous on heparin affinity chromatography, fractionating into three peaks of activity. Although these peaks differed in dose-response characteristics in agar colony and mitogenic assays, each activity was similarly inactivated by heat, acid treatment, and sulfhydryl reduction. Each of the heparin derivatives also behaved similarly on gel filtration and diethylaminoethyl chromatography. Leukemia-derived transforming growth factor was not mitogenic for normal or leukemic lymphocytes or granulocyte/macrophage progenitors. Therefore, a direct or autocrine function for this activity seems unlikely.