THE KINETICS OF HLA CLASS-I ELUTION AND THE RELEVANCE FOR THE USE OF HLA-ELUTED PLATELET TRANSFUSIONS

HLA-eluted platelet transfusions may be feasible for transfusion in HL A-alloimmunized refractory patients, but the reduction in HLA expressi on after elution is variable. Using different anti-HLA antibodies dire cted against the HLA class I complex, the heavy chain, beta 2-microglo bulin (beta 2M) and the intracytoplasmatic part of the heavy chain, we investigated factors which influenced the HLA reduction by flow cytom etry. Reduction of HLA expression by acid treatment resulted in an alm ost complete removal or KLA class I molecules from the site of the int racytoplasmatic part of the heavy chain. Re-expression of HLA heavy ch ain, beta 2M and some of the trimolecular complex (comprised by beta 2 M, heavy chain and peptide) occurred within 4 h. This was presumably L -he result of adsorption from the supernatant (eluate or plasma). Afte r immediate removal of the eluate and incubation in plasma-free supern atant no re-expression of HLA occurred after a 4 h interval.