[Superficial origin of erythrocytic chalone in polycythemia in vitro]

It was shown in the culture of rat bone marrow cells in experimental polycythemia that the chalone activity of erythrocytic chalone considerably drops in the presence of phytohemagglutinin (PHA). The chalone inhibits the agglutinating activity of PHA with respect to bone marrow cells. Absorption of the chalone on the immobilized PHA leads to disappearance from it and of PAS-positive bands recorded electrophoretically and to a strong decrease in PAS-negative band intensity. Experiments with preliminary incubation of rat red cells before preparation of the chalone suggest that in the course of its preparation two polypeptides one of which is PAS-positive are released into the medium. It is suggested that the chalone includes superficial membrane proteins of red cells, possibly, in the form of a combination of PAS-positive and PAS-negative bands. Potential mechanisms of chalone release from the surface of cells and features of their action on the cells are discussed.