Disparity between clinical and immune responses in a controlled trial of azathioprine in rheumatoid arthritis

Drugs that interfere with the immune response in vitro, such as azathioprine (AZ), have been used extensively since 1964 in clinical therapeutic trials of autoimmune diseases. However, few adequately controlled studies are available concerning the concurrent effect of AZ on the immune and clinical responses to treatment of rheumatoid arthritis (RA). Thirty patients suffering from classical seropositive RA received AZ (1.5 - 2.0 mg/kg/day) and placebo in a controlled clinical cross-over study for two 12-week periods. Other treatments were kept constant throughout the entire 6 months. In terms of the clinical responses of joint count and grip strength patients receiving AZ improved markedly, in contrast to the placebo group. After 2 months, joint scanning revealed no progress of the disease in patients undergoing AZ treatment. Corresponding with the remarkably beneficial clinical effect of AZ, a significant drop in immunoglobulins was observed. However, since AZ failed to suppress in vivo specific antibody synthesis in RA, the question remains as to whether this drug actually does interfere with the autoimmunogenesis of the disease.

Protein synthesis in vitro by cryopreserved Plasmodium falciparum

Plasmodium falciparum-parasitized erythrocytes obtained from infected owl monkeys (Aotus trivirgatus) and stored in the frozen state retain both the capacity to incorporate 14C isoleucine into protein and to infect animals. The cryopreservation method involves the use of glycerol and the reconstitution of isotonicity after thawing. Animals have been infected from material held for up to 273 days and protein synthesis has been demonstrated in vitro for up to 180 days after freezing. The specificity of protein synthesis as an activity of the parasites was shown by the inactivity of control uninfected erythrocytes stored by the same method. Additional evidence for the specificity of the reaction was obtained from inhibition studies with chloroquine; a 7 X 10(-5) M concentration of the drug resulted in 50% inhibition of the initial rate of protein synthesis.