Detection of T suppressor cells in patients with organ allografts

Specific immunosuppression of host's immune response to donor HLA antigens has been a major goal to clinical transplantation. Recent evidence has been accumulating to show that a distinct population of T cells expressing che CD8(+) CD28(-) phenotype display suppressor function and inhibit Th activat ion and proliferation by modulating the APC function. To assess the presenc e of Ts in transplant recipient's circulation, we have developed a flow cyt ometry method that measures the expression of costimulatory molecules on do nor APC exposed to recipient Th and Ts, Our results demonstrate that quanti tation of the capacity of CD8(+) CD28(-) T cells from patient circulation t o suppress the activation of costimulatory molecules (CD80, CD86) on donor APC offers a reliable tool for monitoring specific immunosuppression agains t the graft in solid organ transplantation. Human Immunology 62, 15-20 (200 1). (C) American Society for Histocompatibility and Immunogenetics, 2001. P ublished by Elsevier Science Inc.