PAF AND HEMATOPOIESIS .4. MODIFICATIONS OF SPLEEN AND THYMUS PAF CONTENTS AFTER A SINGLE-DOSE OF THE CHEMOTHERAPEUTIC DRUG 5-FLUOROURACIL IN MICE

The spleen and thymus of mice were examined for the presence of PAF af ter injection of 5-fluorouracil (5-FU) (200 mg/kg). A significant incr ease of the spleen (P = 0.005) and thymus (P < 0.05) PAF concentration s was noted 48 h after 5-FU infusion. PAF levels in thymus are similar to those of controls from days 4 to 14. By contrast, spleen PAF signi ficantly decreased (0.005 < P < 0.03) from days 7 to 14. Conversely, t he 5-FU administration did not modify the spleen and plasma acetylhydr olase activity, suggesting that the variations of PAF levels in thymus and spleen were mainly due to differences of local PAF production. Th us, the chemotherapeutic drug 5-FU modulates in vivo PAF production in haematopoietic organs of mice. Considering the effects of PAF in the processes of B- and T-cell proliferation and functions, these results could be of importance for the role of PAF during human cancer therapy and haematopoiesis in vivo.