Enhanced fecal excretion of selected immune factors in very low birth weight infants fed fortified human milk.

The amounts of lactoferrin, lysozyme, total IgA, secretory IgA (SIgA), and specific SIgA antibodies to a pool of Escherichia coli O antigens were measured in 96-h collections of feces obtained from 28 very low birth weight infants, 28-30 wk of gestation, studied at 2.5 and 6 wk of age. Eighteen of these infants were fed their mothers' milk fortified with fractions of skim and cream derived from pasteurized, lyophilized, mature human milk (FM) and 10 infants were fed commercial cow's milk-based formula. The concentrations of these selected immune factors in the FM and formula also were measured. Specific SIgA antibodies to E. coli O antigens were detected in the feces of 90% of the FM-fed infants, but in none of the feces of the formula-fed infants. The feces obtained from FM-fed infants had markedly greater quantities of lactoferrin (p less than 0.001), lysozyme (p = 0.006), and IgA (p less than 0.001) than those of cow's milk formula-fed infants. The concentrations of total and secretory IgA were correlated significantly (r = 0.88, p less than 0.001) and 95% of total IgA was SIgA. The fecal concentration of specific SIgA antibodies to E. coli O antigens in FM-fed infants correlated with the concentration of these antibodies in their milk (p less than 0.001). However, there were no direct relationships between the milk concentrations or the infant's intakes of the other selected immune factors and the excretion of these factors in the feces.(ABSTRACT TRUNCATED AT 250 WORDS)