XENOGENEIC EFFECT .3. INDUCTION OF CELL-MEDIATED CYTOTOXICITY BY ALLOANTIGEN-STIMULATED THYMOCYTES IN PRESENCE OF XENOGENEIC RECONSTITUTION FACTOR

Abstract

A supernatant from human mixed leukocyte cultures (MLC), xenogeneic reconstitution factor (XRF), was added to 1-way murine MLC. This supernatant greatly enhances the generation of cytotoxic cells from C57BL/6 or DBA/2 responder thymocytes, as assayed by a standard 51Cr-release assay. This enhancement is dependent upon the presence of BDF1 semi-allogeneic stimulator cells and it results in the generation of cytotoxic cells that are specific for the H-2 type of the stimulating alloantigen. In some experiments alloantigen-stimulated murine spleen cells, when cultured with XRF, showed increased induction of cell-mediated cytotoxicity. XRF contains a cytotoxic-cell activating factor(s) that is functionally similar to those found in murine-derived supernatants; this factor can participate in the generation of cytotoxic cells from precursors present in the murine thymus.