부산대학교 도서관

Variable la antigen expression by macrophages (Mφ) was examined during tumor growth by measuring: i) la antigen masking and immunofluorescence by anti‐la antibody, ii) accessory cell function in concanavalin A (Con A) and mixed lymphocyte reaction (MLR)‐induced T cell proliferation, and iii) Mφstimulatory function in the MLR. Tumor‐induced progressive loss of la antigen expression was shown by immunofluorescence and corroborated by anti‐la blockade of MLR stimulatory activity of normal but not tumor‐bearing hosts (TBH) splenic Mφ. The TBH splenic Mφsupported Con A‐induced proliferation of syngeneic T cells (la antigen‐independent) but did not support syngeneic T cell proliferation in the MLR (la antigen‐dependent). Irrespective of tissue source, normal and TBH Mφdiffered in their MLR stimulatory capabilities. In general, splenic Mφpreparations were better stimulators of allogeneic T cell blastogenesis in the MLR than thioglycollate‐elicited peritoneal Mφ. Kinetic studies with TBH Mφshowed a significant progressive loss in MLR stimulatory activity, which was especially pronounced with peritoneal Mφ. Expression of la antigens by normal but not TBH Mφwere diminished by 24‐h in vitroplating of the peritoneal Mφ. Indomethacin treatment showed Prostaglandin E2was not a direct in vitrofactor in la antigen‐mediated reduction of splenic MφMLR stimulatory activity. Taken together, these data delineate a loss of Mφla antigen expression, resulting in a decrease in la antigen‐mediated functional activities during tumor growth.