Expression ofendogenous retroviral glycoprotein 70byantigen- activated cytotoxic andsuppressor Tlymphocytes ofmice

ABSTRACT Concanavalin A-stimulated murine spleen cellsandantigen-stimulated Blymphocytesofnormalmiceexpressanantigen that reacts withgoatantiserum against glycoprotein (gp) 70. Structural analysis ofthis antigencharacterizes it as endoge-nousviral gp7Othat is mostlikely ofxenotropicorigin. ActivatednonspecificTsuppressorcellsandcytotoxic T lymphocytesexpressendogenousviral gp7O, whereasnonactivated mouse TorB lym-phocytes donot. Thepresence ofendogenous retroviral gp7O isthus a novelmarkerfor activated mouse lymphocytes in general. The major viral envelope glycoprotein, gp70, ofmurine typeCviruses (1) is also found in the cell membrane ofvirus-pro- ducing cells (2). It has been suggested that the expression of gp70 mightbelinked to processes ofcellular growth or differ- entiation (or both) (3, 4). Thesynthesis ofendogenous type Cviruses hasbeen demonstrated in mouse lymphocytesafter ac-tivation by mitogens or alloantigens during the graft-vs.-host(GvH) reaction (5, 6). Viral gp70can beexpressed