Papain allergy and surgical risk.

If, as a new study suggests, about 1 percent of individuals with allergies are sensitive to an enzyme common in meat tenderizers, then 500,000 or more Americans may risk serious reactions if they decide to undergo one type of back surgery.

In the October ANNALS OF ALLERGY, researchers at the Texas Tech University Health Sciences Center in El Paso, and the University of Tennessee Center for the Health Sciences in Memphis, report that the food additive papain, extracted from the papaya plant, produced allergic reactions in five of 475 subjects with positive skin tests to routinely tested allergens. This first attempt to define prevalence rates of papain hypersensitivity in people with allergies is significant for its possible relationship to chemonucleolysis--the injection of chymopapain to dissolve herniated lumbar disks. A guest editorial in the same issue points out that consumers ingest increasing amounts of papain in fast-food products, and approximately 100,000 chemonucleolysis procedures are performed in the United States each year.

Papain, the active ingredient in many commercial meat tenderizers, also is found in contact lens cleansing solutions, as a digestive aid in health food stores and as a reagent in pharmaceutical and brewing processes. Cross-reactivity between papain and chymopapain has not been proven by laboratory studies. But about 1 percent of chemonucleolysis patients exhibit anaphylactic (allergic) reactions, and some individual allergy clinit patients show positive test results for both enzymes.

Symptoms of papain allergy, which include itching, headaches, abdominal complaints and conjunctivitis, may appear after cooking or eating tenderized meat. There have been relatively few reports of serious reactions to papain. Nonetheless, the researchers suggest, the possibility of reaction to injected chymopapain warrant concern. A communication from doctors in Ohio and Ontario in the same issue reports five out of six patients with positive skin tests for chymopapain reacted to the therapeutic injection of the enzyme, one seriously. Although the number of patients tested was small and the results preliminary, the authors assert that "recognition of the potential reactor ... is of major importance since there are alternative methods of treatment of [herniated disks]."