New concepts of allergy to cow's milk.
CMA is a diagnostic and therapeutic problem in the field of pediatrics. The response to oral cow's milk challenge was evaluated in patients with suspective CMA. To investigate immune mechanisms in different subtypes of CMA, suppressor activity, in vitro IFN-gamma and IL-4 generation, eosinophil activation and humoral immune response were measured. Also, changes in the function of the immune system were evaluated when patients had clinically recovered from CMA. The results of different measurements were correlated with the patients' clinical response to cow's milk challenge. The prechallenge suppressor activity was found to be low in patients with challenge-proven CMA when compared with those clinically negative to oral cow's milk challenge but had normalized after a 4-18 month milk-elimination period in patients who had recovered from CMA. IFN-gamma generation was low in patients with active CMA but had clearly enhanced in patients recovering from CMA. The serum concentration of ECP increased significantly during oral cow's milk challenge in patients with cutaneously manifested CMA. Measured by the ELISPOT method, the patients with active CMA mounted a high, non-antigen-specific immune response but were unable to direct the antigen-specific response, especially in the IgA class. After a follow-up of a mean 13.5 months on cow's milk elimination diet, the immune response to cow's milk antigens had developed in patients who had recovered from CMA. The development in the capacity to mount an adequate immune response to specific protein antigens, especially in the IgA class, can be interpreted as deriving from the development in T-lymphocyte regulation.(ABSTRACT TRUNCATED AT 250 WORDS)