[Age-related changes in the growth-stimulating effect of serum on BHK-21 cells].

The growth-stimulating effect of two calf and adult animal serum ultrafiltrates (with molecular weight of the components up to 100 000 dalton) on BHK-21 cells has been compared. The growth-stimulating activity of the calf serum ultrafiltrate was much greater. Aggregation of cells--the result of their reduced adhesion to the substrate--was much less pronounced in the presence of the calf serum ultrafiltrate than in the medium with the serum ultrafiltrate of adult animals. The data obtained show that the components containing in the studied ultrafiltrates (mol/wt up to 100 000 dalton) and not gamma-globulins (mol/wt 150 000 dalton), as it was considered earlier, primarily determine the ageing change of growth-stimulating activity of the serum. It should be suggested that the different influence of ultrafiltrates on cell adhesion is due to the presence of factors of adhesion with molecular weight up to 100 000 dalton in the calf serum and to its absence in the serum of adult animals.