Anti-CD45RB and donor-specific spleen cells transfusion inhibition allograft skin rejection mediated by memory T cells.

Donor-reactive memory T (Tm)cells mediate accelerated rejection, which is known as a barrier to the survival of transplanted organs. Selective interference with the anti-CD45RB monoclonal antibody (α-CD45RB) reliably induces donor-specific tolerance. In this study, pre-sensitization to female C57BL/6 mice with the skin of female BLAB/c mice generated a large number of Tm cells and resulted in rapid rejection of the secondly transplanted allografts. α-CD45RB did induce the tolerance to skin allograft primarily transplanted but failed to induce tolerance in the pre-sensitized mice. Donor-specific spleen cell transfusion (DST) alone also failed to induce the tolerance in the pre-sensitized recipients. Interestingly, combination of α-CD45RB with DST inhibited the rejection induced by memory T cells in the pre-sensitized mice. CD25+ T-cell depletion in α-CD45RB combined with DST therapy recipients could prevent skin allograft tolerance from establishing. In addition, adoptive transfer of donor-primed memory T cells into the tolerant recipients markedly broke the established tolerance. Our findings indicate that α-CD45RB and DST can synergistically inhibit the accelerated rejection mediated by memory T cells and induce long-term skin allograft acceptance in mice.