Differential tissue distribution and ontogeny of DC-1 and HLA-DR antigens.

The tissue distribution and the ontogeny of DC-1 antigens have been investigated and compared with those of HLA-DR antigens. Indirect immunofluorescence (IIF) staining of surgically removed normal tissues from adults with the monoclonal antibody (MoAb) BT3.4 has detected DC-1 antigens in tissues of various embryologic origin. The tissue distribution of DC-1 antigens is more restricted than that of HLA-DR antigens, as the former are not detected in duodenal epithelium, colon mucosa, and ductal mammary gland epithelium. In fetuses up to 26 weeks of age, DC-1 antigens were detected only on cortical and medullary thymic dendritic cells with an anatomic distribution similar to that of reticuloepithelial cells and in endothelial cells of the small intestine. At this stage of intrauterine life, HLA-DR antigens have already reached their full tissue distribution. The tissue distribution and the ontogeny of DC-1 antigens resemble those of their murine counterparts, i.e., the I-A antigens.