Immunological detection of cell surface components related with aggregation of Chinese hamster and chick embryonic cells.

Previous studies suggested that Chinese hamster V79 cells possess two mechanisms for their mutual adhesion, Ca²⁺-dependent and Ca²⁺-independent ones. We could prepare cells with only the Ca²⁺-dependent mechanism intact by dispersing cell monolayers with trypsin (0.01%) containing Ca²⁺. In the present study, we found that cells dispersed with a very low concentration of trypsin (0.0001%) in the absence of Ca²⁺ retain only the Ca²⁺-independent mechanism intact. Fab fragments of antibodies directed against surface antigens of V79 cells inhibited the aggregation of V79 cells by the Ca²⁺-independent mechanism, but did not inhibit the aggregation of these cells by the Ca²⁺-dependent mechanism. These results suggest that the two mechanisms of cell adhesion are based on different cellular components. Molecules responsible for the Ca²⁺-independent adhesion mechanism are probably cell surface components, because they were released from cells by the treatment with 0.01% trypsin without losing their specific antigenicity. The presence of adhesion mechanisms similar to those in V79 cells was shown in neural retinal cells of chick embryos. It was assumed, therefore, that these mechanisms of cell adhesion are generally present among a variety of cell types.