Early nutritional experiments: effects on the humoral and cellular immune responses in mice.

Studies were carried out to determine the effect of varying intake during the suckling period on the immune responses of mice. Female mice were bred in litters of 4, 9 or 20 pups. Litters of nine pups were considered control groups. Overfeeding (litters of 4) during this period did not change the serum protein profile nor the humoral and cellular immunity of the weanling mice, as judged by their plaque-forming cell responses to SRBC and lymphocyte stimulation in vitro by Con A or LPS. Conversely, mice bred in large litters showed, at weaning, decreased serum levels of albumin and alpha-globulins but did not exhibit marked alterations of their immune responses, although they were in a severe state of protein-energy deficiency. After weaning, feeding a normal diet ad libitum normalized all the altered parameters tested in the malnourished mice. However, when malnutrition was followed by intermittent feeding, the studied immunological functions were significantly affected: the humoral, as well as the cell-mediated immune responses were depressed. These observed alterations were not related to changes in the levels of serum corticosterone or zinc. Our findings suggested that differences in the length of dietary deficiency rather than its severity may explain some of the conflicts in reports on functional immune tests in protein-energy malnutrition.