In vitro study of immune tolerance induced by CTLA4-Ig in bone transplantation: The effect on cell proliferation stimulated by lymphocytes and bone supernatant.

To clarify the effect of CTLA4-lg on immune rejection of bone grafts, we observed the effect of CTLA4-lg on lymphocyte proliferation of BALB/C mice stimulated by lymphocytes and bone supernatant of C57BL/6 mice. The splenic lymphocytes and bone supernatant of C57BL/6 mice, as the stimulator cells and stimulator antigens, were cultured in vitro with the splenic lymphocyte of BALB/C mice. At the same time, CTLA4-lg at a dose of 5,10 or 20 &mgr;g/ml and L6 (as control) at 20 &mgr;g/ml were added. Six days later, the incorporation of 3 H-TdR was determined. Results indicated that CTLA4-Ig at a dose of 5, 10 or 20 &mgr;g/ml significantly inhibited the cell proliferation stimulated by lymphocytes and bone supernatant of C57BL/6 mice. The effect was non-cytotoxic. L6 showed no significant inhibition of cell proliferation. CTLA4-Ig can efficiently block the proliferation of alloresponsive T cell stimulated by lymphocytes and bone supernatant of C57BL/6 mice. This study provides a basis for further study of CTLA4-induced immune tolerance of bone grafts.