Evidence of indirect allorecognition in long-term human renal transplantation

The purpose of this study was to investigate indirect alloreactivity in the peripheral blood of long-term renal transplanted patients. We evaluated th e T cell proliferative response to a whole pool of donor cell-derived allop eptides, processed and presented by host antigen-presenting cells (APC), ra ther than to synthetic peptides. For the indirect pathway, proliferation as says were performed using APC-depleted donor cells. Indirect alloreactivity was detected in 57% (8/14) of the patients, 6 of whom presented no evidenc e of rejection, but 2 patients had a diagnosis of chronic rejection. In 4 o f 8 positive cases (50%), proliferation was detected with 5 days of culture , and sometimes indirect alloresponse was the dominant route. We present ev idence that the indirect alloproliferative response to a pool of naturally processed donor peptides is present in the peripheral blood of long-term re nal transplanted patients irrespective of rejection. (C) 1999 Academic Pres s.