Antibody‐induced redistribution of HL‐A antigens at the cell surface

Abstract

Abstract The in vitro binding of anti‐HL‐A antibodies to the membrane of human lymphocytes induces important changes in the distribution of HL‐A antigens on the cell surface. Following either direct or indirect immunofluorescence staining at 0 °C, cell‐bound anti‐HL‐A antibodies are dispersed all over the cell surface. When the washed, stained lymphocytes are warmed and incubated at 37 °C, fluorescent antibodies cluster progressively at the cell surface. They form large spots of fluorescence, and sometimes single caps at one pole of the cell, outside which HL‐A antigens are no longer detectable, but other antigens can still be found. Similar findings were made in electron microscopy, following indirect labeling of HL‐A antigens on human lymphocytes, with ferritin or plant virus as the markers. With the indirect immunofluorescence technique, anti‐human thymocyte antibodies and anti‐mouse H‐2 antibodies were found to induce a similar redistribution of the corresponding antigens. The mechanism and the interpretation of this displacement of surface antigens by antibodies are still unclear and are discussed in terms of membrane structure and immunological significance.