Leukocyte migration inhibition test in children with cow milk allergy

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Abstract
The usefulness of the leukocyte migration inhibition factor (LIF) test to detect cow milk (CM) hypersensitivity was studied in 40 children with suspected allergy to CM. Hypersensitivity was carefully investigated by oral milk challenges, which gave a final confirmation of cow milk hypersensitivity in 12 subjects, and excluded it in the remaining 28 subjects. Leukocyte migration inhibition was measured using .beta.-lactoglobulin (BLG), .alpha.-lactalbumin (ALA), .alpha.-casein (ACA) and bovine serum albumin (BSA) as antigens. IgA and IgG antibodies to these antigens were measured by an enzyme-linked immunosorbent assay, and IgE antibodies to these antigens and to CM by radioallergosorbent test (RAST). Skin prick test with CM was performed in 38 subjects, and with BLG, ALA, ACA and BSA in 29 subjects. Leukocyte migrations was more often inhibited by cow milk antigens in the CM challenge positive (CM+) subjects than in the challenge negative (CM-) subjects. Of the specific milk antigens, ALA was the most potent inhibitor, and gave a positive LIF test result in all CM+ subjects, and significantly (P < 0.02) less often (15/24) in CM- subjects. Also in the skin prick test and RAST, ALA gave positive results more often than the other milk antigens. BLG, ACA and BSA had an inhibiting effect on leukocyte migration, but the difference between the CM+ and CM- subjects was not satistically significant. Two of the 12 CM+ and CM- subjects was not statistically significant. Two of the 12 CM+ subjects had no demonstrable IgE antibodies to CM proteins; both of them, however, had a positive LIF test with at least one of the CM antigens. No significant correlation was observed between leukocyte migration inhibition and the serum levels of IgA, IgG or IgE antibodies to milk antigens. The results of this study suggest that cell-mediated immunity may play a role in cow milk allergy, also in subjects with demonstrable IgE antibodies to CM. Even though the LIF test is sensitive in the diagnosis of cow milk allergy, it is not useful as a diagnostic test, since many challenge-negative subjects had a positive LIF test.