DETECTION OF TGFALPHA-LIKE SUBSTANCES IN MEDIUM CONDITIONED BY HUMAN HISTIOCYTIC LYMPHOMA-CELLS (U937)

The study was undertaken to determine whether TGFalpha-like substances are secreted into the serum-free culture medium conditioned by the hu man histiocytic lymphoma U937 cells. The production of TGFalpha-like p olypeptides by human larynx carcinoma HEp-2 cells was also examined. I -125-EGF binding competition assay in a combination with preincubation with anti-TGFalpha antibodies were used. The obtained data demonstrat e that both cell lines constitutively produced detectable TGFalpha-lik e immunoreactivity. Flow cytometry did not show the ability of U937 ce lls to express EGF receptor which is known to bind specifically TGFalp ha too. In contrast, EGF receptor expression was revealed in HEp-2 cel ls. Possible role of TGFalpha in pathogenesis of lymphoid neoplasias i s discussed.