Elevated serum immunoglobulin E in T cell-deficient infants fed cow's milk.

Serum IgE levels at various ages during infancy were related to the number of T cells assessed at the age of 1 mo and type of feeding. Cow's milk-fed babies with low T cell counts had higher IgE at the ages of 3 and 6 mo than breast-fed babies with low T cell counts. Of the babies fed cow's milk, those with low T cell counts had higher IgE levels than those with normal T cell counts. Onset of cow's milk feeding before the age of 3 mo in babies with low T cell counts was associated with continuously elevated IgE during the first year of life, as compared with babies with normal T cell counts. However, when cow's milk feeding was instituted after the age of 3 mo such a difference was not noted. It is concluded that in T cell-deficient infants there might exist a critical period during which onset of cow's milk feeding is associated with subsequently increased IgE synthesis.