Abstract: Aim Specific immunologic unresponsiveness was induced to provent rejection of org an transplantation.Methods Donor (NIH mouse)H-2 antigen and trichosanthin (TCS)was conjugated to immunotox in (AG^-TCS)by hetero bifunctional reagent SPDP、2-it.The recipient (SD rat)was pretreated by AG^-TCS.In vitro the proliferation of the spleen cell, which was stimulated by donor spleen cell was observed.Results The proliferation of the SD ratspleen cell in vitro was inhibited when stimula ted by donor antigen, but it was activited by PHA.Conclutions The immunologic unresponsivness could be induced by AG^-TCS, which was useful in inducement of transplantation to lerance.

Key words: H-2 antigen, immunotoxin, immunol unresponsivness