HLA-DR expression by adrenocortical cells of the zona reticularis: structural and allotypic characterization

We previously reported that human adrenocortical cells in the zona reticularis of normal glands express antigenic determinants recognized by HLA-DR monoclonal antibodies (MoAbs). In the present study, it is shown that these adrenocortical HLA-DR determinants are present on glycoproteins having similar structural characteristics, regarding subunit composition and molecular weight, to those of HLA-DR molecules present on immunocomponent cells. Furthermore, adrenocortical HLA-DR molecules include serologically-defined genetically-appropriate allotypic specificities, detectable by immunostainings with both HLA-DR human alloantisera and MoAbs against polymorphic HLA-DR determinants. The finding of a normal expression of HLA-DR antigens by these highly differentiated and biosynthetically active endocrine cells gives support to the notion that MHC class II molecules may perform biological functions in addition to those related to the immune response.