Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccine has been associated with beneficial effects on overall childhood mortality in low-income countries; this cannot be explained merely by the prevention of tuberculosis (TB) deaths. The beneficial effects of BCG vaccine could be the result of either strengthening of pro-inflammatorymechanisms, helping neonates to fight infections, or the induction of an immune-regulatory network restricting overt inflammation and intense pathology. We aimed to study the effect of live BCG on the ability of dendritic cells (DCs) to polarize T-cell responses. Monocyte-derived DCs were matured in the presence or absence of BCG. The DC phenotype was assessed by CD83 expression, interleukin-12 (IL-12) and IL-10 production, as well as for the ability to polarize T-cell responses. Following stimulation with CD40 ligand, DCs matured in the presence of BCG showed enhanced IL-10 and diminished IL-12 production. These DCs primed naive T cells to develop into IL-10-producing T cells, with no T helper 1 or T helper 2 bias. These results suggest that BCG vaccination might result in the development of IL-10-producing DCs as well as IL-10-producing T cells that could contribute to restricting overt inflammation in infants exposed to pathogens and thus lead to lower infant mortality.

The aim of the present study was to determine the influence of serum from formula and breast-fed infants on neutrophil function (as measured by the attachment and phagocytosis of Candida albicans) as well as the chemoattractant activity of the serum. The results indicate that: (a) serum from breast-fed infants induces a greater chemoattractant activity in neutrophils than serum from 3-month-old formula-fed infants; (b) the highest values of the attachment capacity were obtained after incubation of neutrophils with serum from 1-month-old breast-fed infants; and (c) serum from breast-fed infants induces a greater phagocytic capacity against C. albicans in neutrophils than serum from formula-fed infants.