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–Ig 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–Ig at a dose of 5,10 or 20 μg/ml and L6 (as control) at 20 μg/ml were added. Six days later, the incorporation of 3H-TdR was determined. Results indicated that CTLA4–Ig at a dose of 5, 10 or 20 μg/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.