In inbred animals, the approach has succeeded in curing or delaying the onset of various autoimmune diseases, including diseases that are nearly identical to multiple sclerosis and insulin-dependent diabetes in people. Dr. Noel MacLaren of the University of Florida at Gainesville said that in a strain of experimental mice that naturally get an autoimmune form of diabetes, feeding insulin early in life "delays the onset of diabetes and doesn't do them any harm."
Studies in children who face a high risk of developing insulin-dependent diabetes, now called Type 1 diabetes, are expected to get underway soon, Dr. MacLaren said. Youngsters whose blood tests show they have a 20 percent to 50 percent chance of getting the disease within the next five years will be fed small amounts of insulin to see if oral tolerization can keep the disease at bay.
Studies in patients with mild-to-moderate relapsing and remitting multiple sclerosis are already well under way at 12 centers in the United States and Canada. More than 400 of the proposed 504 patients have entered the study, in which two-thirds will get myelin derived from cows and the others will receive a placebo. Over a two-year period, researchers will measure the number of relapses and degree of disability the patients experience, as well as scan their brains for lesions characteristic of advancing multiple sclerosis. In a small, earlier study led by Dr. Weiner and a colleague, Dr. David A. Hafler, of patients with multiple sclerosis, those given the protein had half the number of relapses.
In a study of rheumatoid arthritis involving 280 patients at five centers, half are being given varying amounts of chicken collagen in their orange juice each morning. Results of this study, directed by Dr. David E. Trentham, a rheumatologist at Beth Israel Hospital in Boston, are expected to be available next summer. In a previous smaller study, patients given collagen experienced significantly less joint swelling and tenderness and needed less pain medication than patients who got a placebo. In addition, four patients in the collagen group went into complete remission, an effect that Dr. Weiner said "rarely happens on its own."
At the National Eye Institute in Bethesda, Md., Dr. Robert Nussen-blatt, an ophthalmologist and immunologist, is giving a retinal protein called S-antigen to patients suffering from uveitis. The vast majority of uveitis cases are due to an autoimmune disease, Dr. Nussenblatt said.
"When we began, we were very skeptical," Dr. Nussenblatt said. "But with something as simple as this, we decided it would be a shame if we didn't try it. And lo and behold, it worked." His first study involved only two patients, both of whom were able to stop taking immunosuppressant medication after consuming capsules of S-antigen. When their monthly antigen treatment was stopped, the disease returned, only to be brought to its heels once more when S-antigen feeding was resumed.
Dr. Nussenblatt has started a study of 45 patients with autoimmune uveitis. Some will get cow-derived S-antigen, some will get a mixture of retinal antigens, some will get the mixture plus S-antigen and still others will get a placebo. The test substance will be given at first three times a week, then once a week, then once a month, Dr. Nussenblatt said.
Transplantation studies so far are limited to animals. Dr. Charles Carpenter, an immunogeneticist at Harvard Medical School, said that rats given hearts and kidneys from animals with genetically incompatible tissues did not reject the organs if, prior to transplantation, the recipients were fed certain cell-surface antigens from the donor animals.