EVALUATION OF HLA ANTIBODIES WITH THE PRA-STAT TEST - AN ELISA TEST USING SOLUBLE HLA CLASS-I MOLECULES

HLA-specific antibody, present before or after trans plantation, may a dversely effect graft outcome. Anti body testing by cytotoxicity (CYT) is laborious, requires viable lymphocytes, does not differentiate non -HLA cytotoxic antibody, and cannot be used readily on specimens from patients being treated with cytotoxic antibodies. We have evaluated PR A STAT, an antibody screening kit that uses an ELISA test with soluble HLA class I molecules as targets, We performed 219 tests on a variety of serum specimens, 128 of which were also tested by CYT, There was a highly significant correlation (r=0.78, P<0.001) between PRA-STAT (PS ) and CYT for the detection of IgG antibodies. Of 66 sera reactive in both assays, 18% had identical specificities defined in both, 27% were more reactive in PS than in CYT, 8% were more reactive in CYT, and 47 % had different specificities in the 2 assays, with overlap in slightl y more than half the cases. Of 13 sera reactive only in PS, 2 were fro m non-transfused, nontransplanted males with no evidence of lymphocyte -reactive antibody by antiglobulin tests, PS uses an IgG-specific conj ugate, therefore IgM class I-specific antibodies cannot be identified- however, their presence does affect test outcome, This, as well as the panel composition and interlot reproducibility, are areas we believe need to be addressed, The PRA-STAT system is rapid, does not require v iable cells or complement, and can be automated in part, Resolution of the problems identified here and availability of an IgM-specific conj ugate should make this test system a valuable tool in histocompatibili ty testing.