Protein malnutrition affects the development of b lymphocytes in bone marrow and spleen

Abstract

Protein malnutrition decreases resistance to infection due to the alteration of various physiological processes, including hematopoiesis. This work evaluated the effect of protein malnutrition on the ontogeny and function of spleen and bone marrow (BM) B lymphocytes (LB). Weaning mice were malnourished by protein deficiency for 21d (M). Control mice (C) received balanced conventional diet. In M and C groups it was evaluated: expression of B220, HSA and IgM in BM and spleen cells by flow cytometry, total IgM and IgG levels in culture supernatants of spleen LB, stimulated with LPS or CpG, and proliferative capacity of spleen LB. Malnutrition decreased significantly the total cell number of BM and spleen, mainly affecting the population of LB (B220+). In BM, the M group showed a marked decrease in immature LB population (B220lowHSAhighIgM+/-) (p<0.01), whereas the spleen showed a decrease of mature LB (B220high HSAlowIgM+) (p<0.05), with respect to the C group. Levels of total IgM and IgG in the M group were not different from the C mice. LB proliferative capacity in response to LPS and CpG was similar in both groups. Malnutrition affects B lymphopoiesis in spleen and BM, decreasing production and number of LB, without affecting the functionality of these cells. According to these results, the increased susceptibility to infections in malnourished mice should be, at least in part, due to quantitative rather than qualitative alterations of LB.