Immunoferritin Study of the Distribution of HL.A Antigens on Human Blood Cells

The localization and distribution of human histocompatibility antigens of the HL.A system was studied in the membranes of a variety of peripheral blood and bone marrow cells, using an indirect ferritin-labeled antibody technique. The distribution of specific HL.A ferritin labeling at the cell membrane was found to be discontinuous, forming “patches” similar to those described for H-2 antigens in mice with indirect immunoferritin methods. The importance of the HL.A labeling at the cell surface varied considerably according to the spectrum of specificity of the anti HL.A antisera used. The cell prolongations were never labeled. The HL.A antigens were localized on all nucleated cells studied, including lymphocytes, monocytes, polymorphonuclear leukocytes, granulocyte precursors, stem cells, erythroblasts, leukemic cells and cultured lymphoid cells. However the comparative evaluation of the labeling suggested that the concentration of HL.A antigens is much lower at the membrane of immature cells. HL.A antigens were never detected on mature erythrocytes, but are still present on reticulocytes. These results suggest a heterogeneity of the human cell membrane with regard to the HL.A antigenic expression, and important variations of the concentration of these antigens according to the cell type and degree of differentiation.