The effect of fibrinogen-methotrexate derivatives on HeLa cell growth.

Proteolytic cleavage of bovine fibrinogen with covalently bound methotrexate (MTX) was studied using four different proteolytic enzymes--trypsin, chymotrypsin, pepsin, and cathepsin D and the interaction of the modified fibrinogen (or fibrin) with HeLa cells was investigated. The presence of fibrin-MTX derivative did not induce any significant morphological alternations of cells. The fibrin-MTX derivative in the gel form was solubilized easily by the action of all proteinases investigated, hydrolysis of highly crosslinked denatured fibrin-MTX in suspension proceeded slower.

The effect of folate binding protein on the colony-forming activity of GM-CFC cells in vitro.

A modified method for the preparation of specific folate binding protein was described. The GM-CFC stimulating activity of this SFBP preparation was investigated on tissue cultures of human bone marrow cells. It has been found that in the presence of HPCM the cell proliferation was markedly increased by the SFBP.

Inhibition of phagocytosis of polymorphonuclear leucocytes by adenosine and HoCl3 in vitro.

Phagocytosis of polymorphonuclear leucocytes treated with NaF, HoCl3 and adenosine were studied. The highest concentration used was 25 mM of NaF, 25 mM of adenosine and 5 mM of HoCl3. It was ascertained that these substances, inhibitors of erythrocyte contractile protein, inhibit both phagocytosis and ability of polymorphonuclear leucocytes to change their shape.