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pubmed:abstractText |
The initiation of murine alloantigen-specific cytotoxic T cell responses is macrophage dependent. The requirement for macrophages can be replaced in macrophage-depleted cytotoxic T lymphocyte assay by a soluble factor released from phorbol myristic acetate-stimulated mouse peritoneal adherent cells or P388D1 macrophage tumor cells. On the basis of the cell of origin, m.w. (15,000), and elution profiles on DEAE cellulose and polyacrylamide gels, this macrophage-replacing factor for T cell-mediated cytotoxicity was identical to lymphocyte activating factor (LAF). The stimulatory effect of LAF was totally dependent on the presence of the priming alloantigen. The results presented in this report support the hypothesis that macrophage-mediated antigen-induced T cell activation is dependent on two signals, antigen and LAF.
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