Trypanosoma gambiense: Inaccessibility as a factor in agglutination and binding to host macrophages

Abstract

Organisms were agglutinated by variant specific antiserum from mice, and macrophages adsorbed organisms in the presence of the antiserum. Trypanosoma gambiense gave high agglutination levels with the antiserum in the region of antigen excess and of equivalence in antigen-antibody ratios, and large agglutinating clumps of organisms were observed. Organisms had reduced agglutination levels with the antiserum in the region of slight antibody excess. Small agglutinating clumps of cells and motile “free” organisms which were not in clumps were noted in the region. Agglutinating clumps of organisms were not seen when organisms were treated with the antiserum in regions of advanced antibody excess. When organisms were treated with antiserum in the region of antigen excess, their binding to the surface of macrophages did not occur. Binding was noted with organisms sensitized with the antiserum in the region of antibody excess, and this was optimal in regions of slight antibody excess where large numbers of motile “free” organisms were seen. Macrophages could adsorb fully sensitized “free” organisms. The number of trypanomastigotes bound when cultured macrophages were saturated was calculated to be about 22.3 organisms/cell.