Antigen- and Lectin-Sensitized Murine Cytolytic T Lymphocyte-Precursors Require Both Interleukin 2 and Endogenously Produced Immune (γ) Interferon for Their Growth and Differentiation into Effector Cells

The transition of precursor cells of cytolytic T lymphocytes (CTL) into effector cells is induced by antigen/lectin and through cooperation between T-cell subsets (Cantor and Boyse 1975; Simon et al. 1981). The discovery that the synergistic effect of lymphocytes during CTL development can be replaced by soluble mediators (lymphokines) secreted by T cells (Altman and Cohen 1975; Plate 1976; Wagner and Rollinghoff 1978) and the availability of clonally derived lymphokine sources (Glasebrook et al. 1982) prompted a series of studies on the role of these factors in CTL induction. From these investigations, two types of lymphokine emerged which seemed to be essential for the generation of CTL from their precursor cells (CTL-P): interleukin 2 (IL2), which provides signals for the proliferation of activated CTL-P (Smith 1980; Gullberg et al. 1983), and one or more CTL differentiation factors (CDF), which are considered to induce maturation in developing CTL-P (Raulet and Be van 1982; Wagner et al. 1982; Folk et al. 1983; Kanagawa 1983). However, the exact roles of soluble mediators in CTL induction could not be ascertained because of the difficulties to purify lymphokine preparations to homogeneity and the finding that even lymphokine sources from cloned T-cell lines contained multiple biological activities.