Syngeneic antitumour antibodies in rats: clearance of cell-bound antibody in vivo and in vitro.

Hooded Lister/Cbi rats bearing the HSN.TC fibrosarcoma produced a high-titre non-complement-binding IgG antibody, and tests in vitro indicated that the syngeneic antibody was specific for this tumour. About 1.4 X 10(5) antibody molecules were bound per cell, a figure one eighth that for cells treated with a high-titre allo-antiserum. When tumour-bearer serum was passively transferred into congenitally athymic rats bearing the HSN.TC tumour the antibody was absorbed out specifically, by comparison with control animals or athymic rats bearing an unrelated tumour that was also syngeneic in Hooded rats. The kinetics of loss of antibody from the surface of HSN.TC cells has been monitored in vitro and the antibody has been found to have an extended half-life at the cell surface (greater than 40 h).