title: Limiting-dilution analysis of human CTL differentiation. Requirement for a lymphokine-mediated differentiation signal.
abstract: The induction of human influenza virus-specific memory cytotoxic T lymphocytes (CTL) from CTL precursors (CTLp) was investigated using limiting-dilution cultures and cell lines. Differentiation of maximal numbers of CTLp in limiting-dilution cultures required at least three signals: antigen stimulation, interleukin-2 (IL-2), and a differentiation factor distinct from IL-2. Antigen-specific CTLp proliferated in response to antigen stimulation and recombinant DNA-derived IL-2, but often failed to acquire cytolytic activity unless conditioned medium (CM) from mitogen-stimulated peripheral blood mononuclear cell (PBMC) cultures was added to the cultures. Temporal analysis of the requirement for CM indicated that it was providing a late signal for CTLp differentiation. This analysis was confirmed by developing CTLp cell lines, which were found to proliferate in response to IL-2 and antigen but not to exhibit influenza virus-specific cytotoxicity until CM was added.
mesh_terms: D002454:Cell Differentiation; D003470:Culture Media; D003602:Cytotoxicity, Immunologic; D006801:Humans; D007251:Influenza, Human / Q000276:immunology*; D007370:Interferon Type I / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology; D008222:Lymphokines / Q000494:pharmacology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000473:pathology
chemical_list: D003470:Culture Media; D007370:Interferon Type I; D008222:Lymphokines; D007371:Interferon-gamma