Participation of histocompatibility antigens in capping of molecularly independent cell surface components by their specific antibodies

Abstract

The antibody-induced capping of several cell surface components was investigated by immunofluorescence methods using 2 mouse cell lines, a parental C58 thymoma line and a mutant derived from it lacking TL [thymus leukemia] and H-2 antigens. Other cell surface components were present in approximately equal amounts on the 2 cells. Parental cells treated with rabbit antibodies to T200, a major surface glycoprotein, rapidly formed caps containing T200, but the mutant cells similarly treated showed a uniform surface distribution of T200. With a secondary antibody treatment, the T200 on both cells capped equally well. When the indirect T200 caps were examined using a 2nd immunofluorescent stain for H-2, TL or Thy-1 antigens, all 3 of these antigens or parental cells were co-capped with T200; on mutant cells no staining was found for H-2 or TL, as expected, and essentially unform distribution of Thy-1 was observed. The co-capping of H-2, TL and Thy-1 antigens with T200 on the parent cell is remarkable, because the first 3 components are molecularly independent in lymphocyte cell surfaces. The indirect capping of the viral glycoprotein gp 69/71 similarly induced a co-capping of H-2 and TL antigens on the parent cell. H-2 and related molecules may co-cap with a variety of independent cell surface antigens. Such co-capping of histocompatibility components could play an important role in a proposed dual recognition mechanism of cell-mediated cytotoxicity reactions and other immunologically important cell-cell interactions.