Organ and class specificity of cell adhesion blocking antisera.

Rabbit antisera prepared against embryonic chick liver cells have been characterized using cell cytotoxicity tests, antibody absorption tests, inhibition of cell-cell reaggregation and cell-aggregate adhesion assays. The sera contain antibodies which specifically block embryonic chick liver cell-cell aggregation with no effect on other cell types or embryonic liver cells of other classes tested. Assays with sera absorbed with live cells, neural retina cells, or erythrocytes as well as with sera raised against these cells, indicate that this anti-aggregation effect is not merely the result of coating the cell surface with non-specific antibody. The anti-aggregation specificities of the sera have been checked by absorption experiments with a variety of membrane preparations. These results suggest significant cross-reactivity only between chick liver and kidney, perhaps reflecting the relatedness of the epithelial elements of these tissues. The immunoglobulin G fraction, F(ab')2 and monomeric fragments Fab' retain activity suggesting that the antisera inhibit cell-cell adhesion via blockage of cell surface ligands and not by cell surface modulation effects or cytotoxicity. The organ and class specificities of the antisera suggest that the inhibition of cell-cell aggregation is mediated by the direct binding of antibody to the embryonic chick liver cell adhesion ligand system.