Signal requirements for the in vitro differentiation of cytotoxic T lymphocytes (CTL): distinct soluble mediators promote preactivation of CTL-precursors, clonal growth and differentiation into cytotoxic effector cells.
We describe here that the requirement of accessory cells for the polyclonal activation of high-density (resting) murine T lymphocytes can be bypassed by soluble mediators present in culture supernatants of concanavalin A (Con A)-activated murine spleen cells. Induction of responsiveness is confined to Lyt-2+ T cells; GK 1.5+ T helper cells require signals provided by accessory cells. Using this system the lymphokine signal requirements for the polyclonal activation of Lyt-2+ cytotoxic T lymphocyte (CTL) precursors could be defined. We show that Con A fails to trigger in Lyt-2+ responder T cells the expression of interleukin 2 (IL 2) receptors and assume that this explains why recombinant (rec) DNA-derived IL 2 fails to induce proliferative responses. Complementation of rec IL 2 with an IL 2 receptor-inducing factor (RIF) induces proliferative responses. RIF alone triggers IL 2 receptor expression in 10-12% of Lyt-2+ T cells exposed to Con A. This lymphokine appears to be distinct from colony-stimulating factor 1, IFN-gamma and IL 1. Resting Lyt-2+ T cells cultured in limiting numbers in the presence of Con A, RIF plus rec IL 2 do proliferate, yet exhibit no cytolytic activity. Differentiation into CTL can be brought about by addition of cytotoxic T cell differentiation factor (CTDF). We conclude that the polyclonal activation pathway of CTL from resting CTL precursors can be subdivided into three stages: preactivation, clonal growth and CTL differentiation. Each of these stages appears to be controlled by a distinct lymphokine, RIF, IL 2 and CTDF, respectively.
Hardt
C
C
Diamantstein
T
T
Wagner
H
H
D000818:Animals; D000950:Antigens, Ly / Q000032:analysis; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D002999:Clone Cells / Q000166:cytology; D003208:Concanavalin A / Q000494:pharmacology; D003602:Cytotoxicity, Immunologic; D007376:Interleukin-2 / Q000276:immunology; D008222:Lymphokines / Q000494:pharmacology; D051379:Mice; D008808:Mice, Inbred CBA; D011971:Receptors, Immunologic / Q000276:immunology; D015375:Receptors, Interleukin-2; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology
D000950:Antigens, Ly; D007376:Interleukin-2; D008222:Lymphokines; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D003208:Concanavalin A