Effects of neuraminidase treatment on CFUs properties and CFUs numbers

Incubation of bone marrow cells with Vibrio cholerae neuraminidase decreases the number of CFUs to a minimum of 25% of control numbers. It is shown that this decrease in CFUs numbers is not due to cytotoxic effects of neuraminidase but to a decrease in the spleen seeding efficiency of colony forming cells. Neuraminidase acts in two ways. It removes negatively charged neuraminic acids from membrane glycoproteins and glycolipids and it can adsorb to the cell surface. It is investigated which of the two enzyme effects is responsible for the decrease in CFUs numbers. Inhibition of the enzyme reaction by EDTA prevents to a great extent the decrease in CFUs numbers, while tests with mouse spleen cells and human erythrocytes show that EDTA has no or a positive effect on the adsorption of neuraminidase to the cell surface. This indicates that the neuraminidase induced decrease in CFUs numbers is caused by the enzymatic removal of neuraminic acids rather than by the adsorption of the enzyme to the cell surface.