REVERSIBLE EFFECTS ON B-CELL AND T-CELL OF THE GUT-ASSOCIATED LYMPHOID-TISSUES IN RATS MALNOURISHED DURING SUCKLING - IMPAIRED INDUCTION OFTHE IMMUNE-RESPONSE TO INTRA-PEYER PATCHES IMMUNIZATION WITH CHOLERA-TOXIN

To define the alterations provoked by malnutrition during suckling (20 pups/dam) in the gut-associated lymphoid tissues of rats, Peyer patch (PP) and mesenteric lymph node (MLN) cells were studied by how cytome try. After weaning (21 days of age), rats malnourished during suckling (MNR) showed an increase in the CD4(+) CD45RC(+) subset together with a decrease in the CD4(+) CD45RC(-) subset (P < 0.01). These alteratio ns remained even after 3 weeks of refeeding with stock diet. The CD4()CD8(+) subset was not increased in the MNR, indicating that a release of cortical thymocytes did not occur. At weaning the percentage of CD 4(+)Thy1(+) cells was decreased in the MNR, indicating a low number of cells released from the thymus. When the B cell lineage was studied, we found a decreased percentage of precursors in the bone marrow and a decreased percentage of mature B cells in the periphery. When the MNR were inmunized intra-PP with cholera toxin (CT) after 1 week of refee ding, the specific IgG and IgA and IgM antibody-forming cells (measure d by ELISPOT) were diminished in the PP, MLN, and spleen when compared to the age-matched controls (P < 0.001). These results were coinciden t with the ELISA titers obtained in the sera and in the intestinal flu ids. When CT was administered after 2 weeks of refeeding, the number o f IgM anti-toxin AFC approached control values, but the number of IgA and IgG AFC continued to be low. When 3 weeks of refeeding was allowed before the CT delivery, the immune response in the MNR aproached cont rol values. These results indicate that malnutrition during suckling p rovokes alterations in B and T lymphocytes and produces a lack in the induction of the primary and secondary immune responses in the GALT wh ich reversed after 3 weeks of refeeding. (C) 1996 Academic Press, Inc.