Bacillus Calmette-Guerin down-regulates CD1B induction by granulocyte-macrophage colony stimulating factor in human peripheral blood monocytes

Non-peptide antigens (e.g, glycolipids of microbial origin) presented by mo nocyte-associated CD1 molecules to T cells appear to play an important role in host immunity against tuberculosis and other pathogenic bacteria. Since vaccination with Bacillus Calmette-Guerin (BCG) has limited efficacy, the influence of viable BCG organisms on the induction of CD1b antigen by granu locyte macrophage-colony stimulating factor (GM-CSF) has been tested in adh erent mononuclear cells obtained from peripheral blood of healthy donors. T he results indicate that the vaccine reduces substantially CD1b induction b y GM-CSF. On the other hand, BCG was found to promote a slight increase in the expression of this molecule on target cells not exposed to GM-CSF. Atte mpts to reverse the antagonistic effects of BCG on GM-CSF with high concent rations of GM-CSF, alone, or associated with IL-4, were unsuccessful. Moreo ver, mycobacteria suppression by 10 mug/ml of rifampin, did not affect BCG influence on CD1b induction. The present results suggest that mycobacterium -induced impairment of the CD1 system could play a role in the unsatisfacto ry results obtained with BCG vaccination.