A RAPID FLOW-CYTOMETRY ASSAY FOR HLA ANTIBODY DETECTION USING A POOLED CELL PANEL COVERING 14 SEROLOGICAL CROSS-REACTING GROUPS

Many studies have demonstrated the usefulness of flow cytometry crossm atching (FC-XM) for selection of regraft recipients, and more recently this assay has been shown to correlate with allograft survival in pri mary cadaveric transplant patients, The need now exists for a practica l antibody screening procedure which uses the same methodology, We des cribe here a simple and sensitive method to screen for HLA antibodies by FC using a pool of 6 cells selected to cover the 14 serological cro ssreacting groups defined by Rodey, Screenings of 367 sera (255 primar y transplant sera, 112 regraft sera) received for monthly antibody tes ting were performed by both pooled cell FC and complement-dependent cy totoxicity (CDC) assays, Forty of these sera were also FC-screened usi ng a panel of 16 individual cells for comparison with the pooled cell FC screenings, Analysis indicated a strong correlation between the poo led FC-PRA and the individual cell panel FC-PRA (P = .0001) with mean values of 60% and 73%, respectively, Only 2 of the 40 sera screened by both FC methods resulted in PRAs that differed by > 40%, The majority (82%) of the primary patients did not exhibit HLA antibodies by CDC-h owever, 22% of the CDC negative patients were positive by flow cytomet ry, Females were more likely to be positive by FC (35%) than males (16 %) (P = .0001), Similarly, black patients were more Likely to have FC- demonstrable antibodies (28%) than white candidates (14%) (P = .014), The regraft patients who tested positive by either or all methods had a mean PRA for CDC, pooled FC-PRA, and individual cell FC-PRA of 40, 7 5, and 85, respectively, FC-PRA proved to be a more sensitive techniqu e in both primary and regraft patients.