The precise role of leukocytes and mediators in human milk is still unresolved. Eosinophils are uncommonly detected in human milk and their presence has previously been associated with maternal atopy and development of cow's milk allergy (CMA) in the breast-fed infant. The purpose of this study was to examine the levels of eosinophil cationic protein (ECP) in human milk and to compare the levels with development of allergic diseases in breast-fed infants. Altogether 94 breast-feeding mothers (58 atopic, 36 nonatopic) with their babies were prospectively followed from birth for development of CMA or atopic dermatitis. Colostrum and mature milk samples (at 3 mo of lactation), together with mother's peripheral blood samples, were collected. Milk and blood leukocyte content was evaluated with a light microscope. ECP concentration in human milk was measured by commercial UniCAP method. By the end of a 2-y follow-up, 51 mothers had an infant with CMA, 24 had an infant with atopic dermatitis, and 19 had a healthy infant. ECP concentration in milk was under the detection limit (2 g/L) in all the mothers with a healthy infant, whereas detectable levels were found in 27% of mothers with a CMA infant and in 42% of those with a baby with atopic dermatitis. Measurable ECP in milk was detected in 26% of the atopic and 25% of the nonatopic mothers. Presence of ECP in human milk is associated with development of CMA and atopic dermatitis in the breast-fed infant, but has no direct association with the maternal atopy. Human breast milk provides nutrients and multiple immunologic factors, like secretory IgA, to the breast-fed infant (1). It is known to be an important immunologic support system extending from the mother to her infant during the first months of life. The precise role of leukocytes in human milk is still unknown. In animal studies, milk leukocytes have been shown to pass through the gastrointestinal mucosa of a suckling newborn (2-5). They produce cytokines and mediators, which may be released throughout the gastrointestinal tract (6). In our previous studies, we have found that macrophage is the predominant leukocyte in milk of mothers with a healthy baby, whereas in the mothers with a CMA infant, neutrophils and eosinophils are found in excess (7). We have also shown that decreased function of macrophages is likewise associated with development of CMA in breast-fed infants (8), suggesting that defective immunologic support from mother's milk may interfere with normal development of oral tolerance to food proteins.Eosinophils are mainly tissue-dwelling cells. The bloodtissue ratio of eosinophils has been estimated to be 1:100 (9) Eosinophils are presumably involved in normal immune defense as well as in specific morbid processes including parasitic infections and hypersensitivity reactions (9, 10). Eosinophil granules contain cationic proteins, which have been demonstrated in vivo and in vitro to be tissue-destructive (9). Detection of eosinophil-derived granular proteins reflects earlier degranulation of eosinoph...

We suggest that the high expression of ICAM-1 on peripheral blood lymphocytes may reflect enhanced stimulation of T cells in vivo and their migration to the effector tissues in an early-phase of developing CMA. Furthermore, high ICAM-1 expression may be associated with the presence of multiorgan manifestations of CMA, whereas high LFA-1 expression may reflect the IgE-mediated disease.