The importance of cross-reactions between species: Mouse allo-anti-Ia monoclonal antibodies as a powerful tool to define human Ia subsets

Abstract

Three mouse allo-anti-Ia monoclonal antibodies recognizing epitopes specific for either I-E gene products (H81.98.21 and H40.315.7 Mabs) or shared between I-E and I-A gene products (H82.246.3 Mab), were used to analyze the human Ia molecules against which they cross-react. The results indicated that in the Ia pool of the human B cell line Raji the three Mabs were able to recognize at least three distinct subsets differing each other both in their α as well as in their β subunits. The comparison with the previously defined human Ia subsets NG1, NG2, and DC1 suggested the following similarities: H81.98.21 specific Ia molecules similar to NG1; H82.246.3 specific Ia molecules similar to NG2, and including probably NG1; H40.315.7 specific molecules similar to DC1 in their α subunits and probably heterogeneous in their β subunits with characteristics of the DC1, NG1, and NG2 subunits altogether. The heterogeneity of the human Ia molecules and the possible similarities with the mouse Ia system were discussed.