A new supertypic HLA class II determinant (PL2) differentially expressed with DR7, DRw11(5), DRw13(w6), DRw14(w6), DR3, and DR2 and biochemically localized to DR7 molecules.

A monoclonal antibody, PL2, has been produced that reacts with a new supertypic determinant expressed on the peripheral blood B lymphocytes and B-leukemic cells (B-CLL) from all individuals who are HLA-DR7 and some individuals who are HLA-DR5 positive. The genetic linkage of the PL2 determinant to the HLA region was demonstrated by family segregation studies. When cultured Epstein-Barr virus (EBV) transformed B cell lines were examined, PL2 was again found to be expressed on all cell lines homozygous for HLA-DR7 and the DRw11(5) subtype of HLA-DR5 positive cells, while one DRw12(5) cell line was negative, suggesting PL2 may distinguish between these DR5 subtypes. In addition, using the panel of EBV-transformed B-cell lines, PL2 was also found to be weakly expressed on HLA-DRw14(w6), -DRw13(w6), -DR3, and -DR2 positive cells but was completely absent from HLA-DR1 and -DR4 positive cells, and is probably absent also from DRw8- and DRw10-positive cells. From titration analysis and quantitative absorption studies the PL2 determinant was found to be expressed at quantitatively different levels in the following order: DR7 greater than DRw11, DRw14 greater than DRw13 greater than DR3 greater than DR2. The molecules carrying the PL2 determinant on DR7 cells have been characterized biochemically to be a subpopulation of HLA class II molecules recognized by the DR specific monoclonal antibody, L243. Furthermore, by two-dimensional gel analysis, PL2 immunoprecipitated only two of three beta chains associated with the DR-apha chain, which are the same two chains that carry the DR7 allodeterminants.(ABSTRACT TRUNCATED AT 250 WORDS)