Assay of intercellular adhesiveness using cell-coated Sephadex beads as collecting particles

Adhesion of frog pronephric tumor cells to normal cells cultivated on microcarrier beads

The processes of cell adhesion and active spreading were assessed between frog normal pronephric, pronephric tumor and heterologous liver cells. Confluent monolayers were developed on collagen-coated microcarrier beads, then exposed to homologous or heterologous cells and cultivated with a rotary (orbital) flask culture technique at 23 degrees C. All three cell lines attach and actively spread on the collagen-coated microcarrier beads. Secondary attachment of normal (non-transformed) proliferating cells to their confluent monolayers occurs but cell spreading is restrained. Dissociated pronephric tumor cells adhere and actively spread on the surfaces of normal pronephric cells, and eventually encapsulate them. Normal pronephric cells do not adhere readily to the cell surfaces of pronephric tumor cells grown on microcarrier beads. Tumor cells also attach, actively spread and overgrow heterologous liver cells attached to microcarrier beads. Suboptimal temperatures (17 degrees C) slow tumor cell attachment and spreading on normal cells. Colder temperature (8 degrees C) permits tumor cell attachment and adhesion to normal cell-coated beads but active cell spreading is prohibited. The same temperature retards cell spreading directly on the collagen-coated beads.

Plasma membrane isolation on DEAE-Sephadex beads

A much-simplified method for the purification of plasma membranes of cultured cells is presented, based upon the attachment of viable cells to nitrocellulose-treated DEAE-Sephadex beads, and their subsequent shearing by hypotonic lysis, agitation on a vortex mixer and sonication. The method is suggested by an older procedure involving attachment to poly-(L-lysine)-coated glass or polyacrylamide beads; the preparation involved in the present method, however, is considerably easier, more rapid and less expensive. Recovery of L-cell plasma membrane marker enzyme activities is approx. 25%, while contamination by internal membrane markers is much less than 1%.

Intercellular adhesiveness of H-2 identical and H-2 disparate cells

Using a 2 X 2 design, the collection rates of cells from radioactively labelled single-cell suspensions on cell-coated collecting surfaces were tested for a possible H-2 effect on intracellular adhesiveness. By a statistical procedure, the undesirable variability in the suspension and/or in the collecting surface could be eliminated, and the H-2 specific net effect estimated. In this way it was possible to detect (even on the background of a large non-specific variability) significant reductions of the allogeneic collection rates (i.e. between cells which differed only in their H-2 haplotypes) as compared to the syngeneic standards. It is concluded that cells of a given H-2 haplotype have preferential adhesiveness to syngeneic cells.