Divalent cation-independent aggregation of rat-1 fibroblasts infected with a temperature-sensitive mutant of Rous sarcoma virus.

Rat-1 fibroblasts infected with the temperature-sensitive transformation mutant LA 24 of Rous sarcoma virus have a high rate of divalent cation-independent homotypic cell aggregation when grown at the permissive temperature, 34 degrees. Cells grown at the nonpermissive temperature, 39 degrees, have a low rate of homotypic cell aggregation. Hyaluronic acid is involved in the homotypic aggregation of permissively grown cells since aggregation is blocked by either treatment of the cells with hyaluronidase or the presence of exogenously added hyaluronic acid. Despite their low rate of homotypic aggregation, nonpermissively grown cell are capable of heterotypically adhering to premissively grown cells. The formation of heterotypic aggregates is blocked by treatment of the nonpermissively grown cells with hyaluronidase but not by treatment of permissively grown cells with hyaluronidase. These results provide evidence that the divalent cation-independent aggregation of Rat-1 LA 24 cells is mediated by interactions between hyaluronic acid and other adhesive components on the cell surface.