DETECTION EFFICACY OF SOLUBLE HLA-A, HLA-B ANTIGENS USING 1D-IEF

Soluble HLA class I alloantigens (sHLA class I) can be typed according to their isoelectric points (IEP) after immunoprecipitation by w6/32 monoclonal antibody (mAb) coupled to immunomagnetic beads and focusing . In order to prove the large scale efficacy of this methodology, EDTA -plasma samples from 344 probands HLA-A, B typed by serology were anal ysed by one-dimensional isoelectric focusing and HLA class I specific Westernblot (1D-IEF). In addition, detergent solubilized HLA class I m embrane molecules from approximately one half of the probands were stu died too. Soluble HLA-A24, B7, B18, B62 antigens were identified in ne arly all experiments, whereas A28, B13, and B51 could be detected in a bout 50%. A third group of HLA antigens (A26, B8, B44) could be visual ized rarely. The difficulties of detection might be due to the differe nt affinity of mAb w6/32 to certain sHLA class I gene products or to v ariable amounts of sHLA class I in the plasma specimens. Some modifica tions of the antigen capture technique have already led to a slightly better degree of antigen recognition in 25 probands tested. Thus, HLA- A, B typing using sHLA molecules and 1D-IEF in the assay format presen ted does not yet seem to be a definitive alternative for HLA class I s erology or biochemistry of membrane-bound HLA class I molecules but it should be a promising technique if no cells are available or donor-de rived sHLA allotypes are to be monitored after HLA mismatched organ tr ansplantation.