Fas-resistance in ATL cell lines not associated with HTLV-I or FAP-1 production

A preventive role for human T-cell leukemia virus type-I (HTLV-I) and Fas-a ssociated phosphatase-1 (FAP-1) in Fas-mediated apoptosis has been reported in HTLV-I-infected cells. In the present study, we examined whether these molecules increased during the acquisition of Fas-resistance in adult T-cel l leukemia (ATL) cell lines. SO4, ST1 and KK1 are Fas-sensitive ATL cell li nes, and produce small amounts of HTLV-I in vitro. Although their subclones RSO4 and RST1 are completely Fas-resistant, they produced an equivalent am ount of HTLV-I to SO4 and ST1, Moreover, FAP-1 mRNA was not detected in the se cell lines irrespective of Fas sensitivity. Thus, Fas resistance in ATL cells was not directly associated with the increased production of HTLV-I o r FAP-1. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.