IEF ANALYSIS OF HLA MOLECULES IMMUNOPRECIPITATED BY PUTATIVE ANTI‐CLASS I‐LIKE ALLOANTISERA

Two human alloantisera, previously described as possibly detecting new beta 2‐microglobulin associated proteins, selectively expressed on HLA‐A2 and HLA‐A1 phytohaemagglutinin (PHA)‐activated lymphocytes, immunoprecipitated only molecules with the same isoelectric point as HLA‐A1 and A2 products. This result suggests that the selected alloantisera do not react with the products of an HLA class I locus different from ABC but probably recognize a new epitope arising on HLA‐A molecules upon conformational changes consequent to cell activation.