Low doses of recombinant interleukin-2 enhance delayed type hypersensitivity to PPD in mice infected with Mycobacterium bovis-BCG and fed a diet supplemented with vitamin A acetate.

Mice infected intravenously with high doses of M. bovis, strain BCG, showed a marked impairment of delayed-type hypersensitivity to PPD evaluated in vivo as skin test and in vitro as splenocyte blast transformation. Furthermore, this state of unresponsiveness is partially reversed either by the intraperitoneal injection of high doses of IL-2 or by feeding mice a diet supplemented with vitamin A acetate (VAA) at least 6 weeks before the BCG injection. This paper shows that low doses of recombinant IL-2 together with a supplementation of VAA in the diet at the moment of BCG infection is sufficient to induce in mice a positive skin reaction and blast transformation to PPD.