H-2K and H-2D antigens are independently regulated in mouse embryo fibroblasts

The concentration of MHC class I (H-2K and H-2D) antigens on stimulating cells and target cells may influence the induction of responses in cytotoxic T-cell precursors, and the efficiency of cytotoxicity mediated by activated T cells, respectively. Using FACS analysis, we found that exposure of BALB/c mouse embryo fibroblasts (MEF) under different culture conditions to the supernatant from concanavalin A(Con A)-stimulated splenocyte cultures (CS) could result either in H-2K antigens increasing significantly more than H-2D antigens or in H-2D antigens increasing significantly more than H-2K antigens. Furthermore, we observed that the concentrations of H-2K antigens on MEF that were not exposed to CS in vitro could vary independently of H-2D antigen concentration during a period of several days in vitro. Thus we propose that the cell surface concentration of H-2K and H-2D antigens may be independently regulated, and we discuss how such regulation may be biologically advantageous during protective T-cell responses.