Late treatment of murine lupus erythematosus with dactinomycin. II. C1 and antibody to DNA.

(NZB x NZW)F1 hybrid (B/W) female mice were treated intermittently with dactinomycin beginning at 6--6.5 months of age. Survival was greatly prolonged relative to control mice. IgG antibody to DNA did not decline significantly in the treated mice until they were more than 18 months old, but circulating levels of the first complement component (Cl) rose during the first 4 weeks of treatment and were back into the normal range after 8 weeks. Thus these two humoral indexes of disease activity varied independently, and only Cl reflected the improved status of the treated mice.