Cell surface oligosaccharide modulation during differentiation. I. Modulation of lectin binding.

IMR-90 human lung fibroblasts exhibit quantitative and qualitative changes in their cell surface oligosaccharide expression as a result of low-density growth, contact inhibition of growth and changes in population doubling level (PDL). Binding of Concanavalin-A (CON-A), wheat germ agglutinin (WGA) and Ricinus communis (RCA-120) was shown to decrease by 20-40% as the cells advanced through their lifespan (but significantly before morphological manifestations commonly associated with senescence, which occur at approximately PDL 45). The binding of Dolichos biflorus agglutinin (DBA) increased by 100% over the same time interval. These changes were detected by quantitation of FITC conjugated lectins on single cells and the use of a sensitive analytical biotin-avidin-enzyme amplification assay on whole populations of cells. These studies were performed on randomly growing cultures. These results suggest an important and dynamic role for the cell surface oligosaccharide in growth control and cellular senescence.