In vitro cell-mediated immunologic assay for cow's milk allergy.

The production of a lymphokine, the leukocyte-migration-inhibition factor (LIF), by peripheral blood lymphocytes in response to an in vitro challenge with bovine beta-lactoglobulin was assayed in infants and children suspected of having allergy to cow's milk protein. Of the patients studied, 24 had cow's milk allergy, 24 were normal control subjects, 18 had recovered from milk allergy, 10 were newborns, and 10 were babies suffering from acute gastroenteritis. All patients with milk allergy demonstrated significant LIF production in response to beta-lactoglobulin (23.5% +/- 6.4%). In the normal control subjects, LIF was 3.1% +/- 4.3% (P < .0005). Only two of the 24 control subjects and two of the ten newborns had high-normal values bordering on the positive. None of the ten babies with acute gastroenteritis gave a positive response. Most of the children who had recovered from milk allergy and were ingesting cow's milk had negative assays. This cell-mediated immune assay is shown to be a reliable test for the diagnosis of sensitivity to milk protein in infants and children, and for determining dietary treatment and when this treatment can be safely terminated. In most cases, its use should eliminate the need for the potentially dangerous and ethically questionable provocation test, as well as the need for repeated intestinal biopsies.