PROTECTIVE EFFECT OF AN ACIDIC GLYCOPROTEIN OBTAINED FROM CULTURE OF CHLORELLA-VULGARIS AGAINST MYELOSUPPRESSION BY 5-FLUOROURACIL

An acidic glycoprotein prepared from a culture of Chlorella vulgaris ( CVS) was examined for its' protective effect on 5-fluorouracil(5FU)-in duced myelosuppression and indigenous infection in mice. Subcutaneous administration of CVS greatly reduced the mortality of non-tumor-beari ng mice given a high dose of 5FU, and could increase the LD(50) value of 5FU for these mice. After 5FU treatment, indigenous infection devel oped probably as a result of the impairment of the host defense system . CVS reduced the incidence of indigenous infections and this effect w as attributable to the acceleration of recovery from 5FU-induced myelo suppression. Early recovery of hematopoietic stem cells, or cells resp onding to interleukin-3 or granulocyte/macrophage-colony-stimulating f actor, was especially observed in the bone marrow of CVS-treated mice on days 4-9 after the injection of 5FU. When tumor-bearing mice were g iven CVS during treatment with 5FU, CVS prolonged the survival of mice without affecting the antitumor activity of 5FU. In addition, CVS was itself shown to exert an antitumor effect. These results suggested th at CVS may be beneficial for the alleviation of side-effects in cancer chemotherapy without affecting the antitumor activity of the chemothe rapeutic agent.