Specific sHLA in healthy donors and donor-specific sHLA in renal transplant patients.

We studied cadaver kidney transplant recipients to determine if their serum levels of donor-specific class I sHLA correlated with graft outcome. Testing of sHLA was performed by an ELISA sandwich assay using allospecific monoclonal trapping antibodies and anti-beta2-mu detecting antibody. Sufficient sHLA sensitivity (<1 ng/ml) was achieved by using two synergistic trapping antibodies. Suitable antibodies were available for A2 and B7, and data were collected for these two antigens. Stability of these sHLA was determined in plasma and serum as were ranges of normal and background levels. Background levels varied substantially. Five A2- recipients of A2+ grafts and 5 B7- recipients of B7+ grafts were studied with appropriate sHLA levels measured pre-transplant and at intervals post-transplant. Graft outcome was assessed by serum creatinines, renal biopsies and/or therapy for rejection. In the 5 patients (3 A2- and 2 B7-) whose post-transplant donor-specific sHLA never exceeded immunological complications (e.g., post-operative ATN, ureteral obstruction) did not affect the correlation. In the 5 patients with post-transplant levels exceeding pre-transplant levels, subsequent evidence of rejection was observed. Periodic measurement of donor-specific sHLA should be a useful instrument for monitoring renal allograft rejection.