ABSTRACT
Although there is no reliable single laboratory test available for the diagnosis of cow's milk allergy, if an allergic mechanism is suspected, a number of laboratory studies may be useful in delineating specific proteins responsible for these disorders. In the current study we analyzed in vitro lymphocyte proliferation assays, specific secretion of TNFalpha in supernatant cultures and specific IgE, IgG, and IgA in a group of patients with hypersensitivity to cow's milk antigens. The stimulation index against a cow's milk antigen mixture, alpha-lactalbumin, beta-lactoglobulin, and casein was significant higher in the group of patients maintained on cow's milk-free diet for less than 4 months compared with the values observed in the control group and in the group of patients without a close contact to cow's milk proteins. A significant increase in TNF-alpha secretion was observed in supernatants from patients with close contact to cow's milk (CM). Specific IgE was detected in 59.3% of the patients, with higher specific IgE levels in patients who were not positive for the proliferation assay, suggesting a clear difference in the two mechanisms proposed as effectors in this disease. No differences in specific IgG and IgA levels were observed between the patient group and the control group, with a great dispersion among individuals in all groups tested. We conclude that a combination of the assays tested in this study, such as proliferative assay of peripheral blood mononuclear cells to CM, the quantitation of TNFalpha in culture supernatants, and serum specific IgE determination, are useful laboratory tests to identify cow's milk allergy among patients with immediate and non immediate adverse reactions, reducing the need for food allergen challenges in young children.