Effect of fetal protein malnutrition on the postnatal structure and function of alveolar macrophages

To test the hypothesis that intrauterine malnutrition may alter ontogeny of the host defense system, an animal model of fetal protein deprivation was developed. Young adult female rats were fed either a deficient (8% protein) diet or a normal (25% protein) diet for 10 days before insemination and throughout gestation. Offspring of the malnourished animals showed significant growth retardation and were hypoproteinemic. Lavageable pulmonary cells from both groups of neonates were similar with respect to number (2.05 x 10(5) cells per animal), type (95% macrophages), size (approximately 10-micrometer diameter), ultrastructure, and presence of surface receptors for IgG. Despite these similarities, alveolar macrophages from malnourished neonates were significantly impaired in their ability both to ingest and to kill Candida tropicalis. Nutritional supplementation of nursing females reversed these functional macrophage defects in their offspring by the time that weaning occurred. These data indicate that fetal protein malnutrition affects macrophage function but that with postnatal nutritional supplementation these defects are rapidly reversed.