Conversion of human fibroblasts to tissue macrophages by the Snyder-Theilen sarcoma virus (ST:FeSV): tumouricidal effects on K-562 and Daudi tumour cell lines in monolayers and in agar suspensions.

We have previously demonstrated the conversion of human fibroblasts (HF) to tissue macrophages by transduction with the Snyder-Theilen feline sarcoma virus (ST:FeSV) [1-3]. The ST:FeSV-induced TM have been characterized both phenotypically and functionally, including their tumouricidal potential against colon adenocarcinoma (LS 180) cells. The present results show that ST:FeSV-induced TM produced significant lysis of K-562 tumour cells, but essentially no lysis of the Daudi tumour cells. Lysis of K-562 tumour cells by the ST:FeSV-induced TM was considerably more effective in 1% than in 10% FCS. Addition of TNF-alpha caused only a slight increase in the extent of lysis of K-562 tumour cells by the ST:FeSV-induced TM. Coincubation of the ST:FeSV-induced TM with K-562 cells in agar medium resulted in the inhibition of tumour cell proliferation. The results indicate that ST:FeSV-induced TM are potent oncocytotoxic agents of K-562 tumour cells, but are considerably less effective against the Daudi tumour cells.