Antigenic determinants of the W28 molecule different from but spatially close to W28 determinant.

The existence of two allelic determinants, subtypic to W28 (named TO54 and TO55), and of an antibody cross-reacting W28 times HL-A10, is demonstrated. These new determinants have been studied by means of population and family studies and with the following serological techniques: absorption, elution, lysostrip and blocking by F(ab)-2 fragment. The results suggest that determinants TO54 and TO55 are very similar each other and are spatially close to the supertypic factor.