Nonlymphoid cultured cells possess a system controlling cellular compatibility

We show that various nonlymphoid cultured cells can activate the production of cytotoxic factors in response to direct contact with cells or a differe nt kind. Accumulation of cytoxic factors in the medium was detected h after contact of K562 and L929 cells or alter contact of L929 cells with purifie d membranes of Kj62 cells. TNF-alpha or immunologically related proteins, o r both, but not Fas-ligand or lymphotoxin, were also accumulated in membran es cells shortly alter these cells had been allowed to contact each other. The cytotoxic factors expressed of K562 and L929 c by nonlymphoid cells tri gger apoptosis of target cells. These observations strongly suggest that no nlymphoid cells possess molecular mechanisms controlling cellular compartib ility. J. Cell. Biochem. 78:186-196, 2000. (C) 2000 Wiley-Liss. Inc.