Combating corneal transplant rejection.

Corneas are the most commonly transplanted tissues, but they are attacked by the immune systems of at least 10 percent of the people who receive them--despite topical antirejection drugs. For these people, subsequent corneal transplants fail 65 percent of the time.

To prevent such failures, researchers performed corneal transplants in mice that they had immunized against rejection. For the immunization, the researchers took skin from the donor mice, processed it with enzymes, mixed it with a harmless component of cholera toxin, and fed it to the recipient mice for 10 days before the transplant. More than 90 percent of the transplants into immunized mice succeeded, even without antirejection drugs. Mice on dosage regimes begun on the day of the transplant maintained an 80 percent acceptance rate without antirejection drugs.

All of the mice that weren't immunized or given antirejection drugs rejected the corneas. The researchers reported portions of their study in the September British Journal of Ophthalmology.

"It appears from these results that we can ... reprogram the immune system," says Jerry Y. Niederkorn, an immunologist at the University of Texas Southwestern Medical Center at Dallas. To prepare doses for human patients, doctors would need to collect from the donor a skin patch the size of two $1 bills, he says. The processed tissue could be fed to recipients in gelatin capsules. His team is currently seeking approval for a human study next year.