Inhibition of bleomycin-induced pulmonary fibrosis by cobra venom factor.

A single dose of cobra venom factor, a known, potent depletor of serum complement, has recently been reported to be highly effective in inhibiting lung collagen deposition at 7 days after bleomycin treatment. The present study shows that this is associated with suppression of the bleomycin-induced increase in collagen synthesis, down to virtually normal levels. There is also a concomitant reduction in tissue free proline pool size. No significant effects are noted in noncollagenous protein synthetic rates. This inhibitory effect is not seen at 30 days after bleomycin and is correlated with a return to normal levels of serum complement hemolytic activity. These data suggest an important role for complementary activity in the lung's fibrotic response to bleomycin.