Six of 9 patients with previously documented adverse reactions to allopurinol exhibited transformation of their peripheral blood lymphocytes when these were exposed in vitro to the allopurinol metabolite, oxypurinol. In 2 of these subjects, intradermal skin challenge was positive at 48 hours with either allopurino1 or oxypurinol. The evidence presented suggests that some adverse reactions to allopurinol represent delayedtype hypersensitivity to oxypurinol.

Ross River virus has been incriminated in the etiology of many sporadic and epidemic cases of polyarthritis in Australia and the Pacific. Both synovium and synovial exudate fluid recovered from the knee of an epidemic polyarthritis patient showed a predominantly mononuclear leucocyte infiltrate. Infectious virus could not be recovered from the synovial exudate. Functional natural killer cells were detected in the synovial fluid. Their level of cytotoxic activity was similar to that detected in the peripheral circulation.

The thiol status of patients with rheumatoid arthritis is significantly different from that of controls. Plasma thiol levels are lower, albumin thiol reactivity is altered and intracellular thiol levels measured after hemoglobin precipitation are increased. These variations correlate with other indices of disease severity and are one measure of a disturbance in the degree of oxidation of the blood. Penicillamine, in common with other effective therapeutic agents, produces an increase in serum thiol concentration. It causes a greater effect on serum thiol reactivity than other drugs and in particular it increases 'fast reacting' thiol levels without significantly altering the 'slow reacting' thiol level.