NEW YORK. Reuters Health, February 26, 2002. Studies in mice suggest that protein A, a toxin produced by Staphylococcal bacteria, may have a therapeutic role in lupus. Dr. Gregg J. Silverman, of the University of California, San Diego, presented his group's findings this week in New York during a gathering of lupus researchers sponsored by the Alliance for Lupus Research.

In studies in mice and primates, protein A injections destroyed up to one-third of circulating B cells--which have been implicated in the pathogenesis of lupus. When a highly purified recombinant form is injected into the animal it binds the immunoglobulin on the surface of lymphocytes and causes them to undergo a series of steps that results in programmed cell death. It is an efficient mechanism which does not seem to have any effect on the rest of the body. It acts like a superantigen for B-lymphocytes that are responsible for different aspects of lupus pathology. The goal is to determine which patients may be helped by this approach.

Dr. Don Segal, of the University of Pennsylvania, has recently found some that suggests that patients with autoimmune thrombocytopenia may be good candidates for initial trials since one aspect of lupus is autoreactivity to platelets. The antibody response appears to be produced by B lymphocytes that would be specifically targeted by this toxin but only a subset of B lymphocytes are responsible for making these pathogenic autoantibodies, and these use a particular antibody gene from the VH3 family, which turn out to be exactly and solely the ones targeted by the toxin.

Dr. Silverman's research is funded by a grant from the Alliance for Lupus Research.

Awaiting permission from Reuters.

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