ASSESSMENT OF 3 METHODS OF EVALUATING SOLUBLE CLASS-I HLA MOLECULES IN CELL-CULTURE SUPERNATANTS AND SERUM SAMPLES FROM THE 2ND INTERNATIONAL WORKSHOP ON SOLUBLE HUMAN-LEUKOCYTE ANTIGENS

Three methodologies were compared in assessing sHLA specificities in c ell culture supernatants and serum specimens from the Second Internati onal Workshop on sHLA: CDC inhibition, FC inhibition, and cellular ELI SA inhibition. Initially, the CDC inhibition assay used polyclonal ant isera in commercial HLA-phenotyping trays to confirm known specificiti es and screen for unknown specificities in 31 specimens. Although part ly successful, critical limits were imposed by the variable antiserum titers. Thus, using pools of these same antisera and renal transplant recipient antisera, the FC inhibition assay was employed to determine the endpoint serum titers before confirming the known sHLA specificiti es. Of 25 specimens, four were not confirmed and five gave weak inhibi tory reactions. The cellular ELISA inhibition assay, incorporating pat ient sera and mAbs toward three HLA, successfully confirmed all three known specificities in eight selected workshop specimens. Each methodo logy had advantages and disadvantages, but all three methods were succ essful in detecting and identifying sHLA class I specificities. Succes s, however, was dependent on the initial characterization (specificity and titer) and titration to end point (appropriate for each method's sensitivity) of each antibody preparation.