Cell adhesion mediated by glycolipids

Abstract

ADHESION between adjoining cells is a fundamental biological event, preceding both morphogenesis and organogenesis and also providing the basis for cellular recognition and membrane fusion^1–4. Adhesion is apparently mediated by carbohydrate moieties on the plasma membrane as shown in studies of sugar transferases^5–7 and glycosidases⁸. A number of mechanisms such as the antigen–antibody reaction^9,10, the specific sugar transferase–substrate complex formation¹¹ and hydrogen bonding¹¹ between closely opposing carbohydrate chains have been proposed for the specific and nonspecific adhesion of cells, but the relevant surface molecules have not yet been isolated or identified. Two types of cell adhesion have been described: one is the reaggregation of dissociated animal cells in serum which may involve antibodies^9,10 or unidentified components of serum such as the conglutinin¹². A second type of adhesion occurs in the absence of serum, and is probably regulated by glycoprotein factors^13,14. Recently we found that lipid particles containing phospholipids or glycolipids were agglutinated by serum and that glycolipid particles adhered most strongly to tissue culture cells even in the absence of serum¹⁵. We report here that lipids, in particular glycolipids, could mediate adhesion of animal cells.