The tuberculosis vaccine induced an interleukin-10 producing T-cell population with no T helper 1 or 2 bias in vitro. While this may restrict excessive inflammation (beneficial) it could also act as an immunosuppressant.

PMID: 

Immunology. 2007 Jun ;121(2):276-82. Epub 2007 Mar 20. PMID: 17371543

Abstract Title: 

BCG stimulated dendritic cells induce an interleukin-10 producing T-cell population with no T helper 1 or T helper 2 bias in vitro.

Abstract: 

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.

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