No abstract

SummaryThe guinea pig model of low-dose pulmonary tuberculosis has been used to study the pathogenesis of infection as well as the mechanisms of bacille Calmette-Guérin (BCG) vaccine-induced resistance. We investigated the function of lung cells from naive and BCG-vaccinated guinea pigs after enzymatic digestion of lung tissue with collagenase and DNase I. The total lung digest cells proliferated poorly to purified protein derivative (PPD) but comparatively better to ConA as assessed by

Gamma interferon (IFN-␥

To determine whether

The effect of Mycobacterium bovis BCG vaccination on interleukin-1␤ (IL-1␤) or regulated-upon-activation, normally T-cell-expressed and -secreted chemokine (RANTES) mRNA expression in guinea pig spleen cells stimulated with concanavalin A, lipopolysaccharide (LPS), phorbol myristate acetate (PMA) plus ionomycin, or purified protein derivative (PPD) was studied in vitro. Similarly, peritoneal exudate cell-derived macrophages from naïve and BCG-vaccinated guinea pigs were infected with M. bovis BCG, Mycobacterium avium, the attenuated Mycobacterium tuberculosis H37Ra strain, or virulent strains H37Rv and Erdman of M. tuberculosis. Total RNA was subjected to Northern blot analysis using probes generated from guinea pig IL-1␤ or RANTES cDNA. Although IL-1␤ and RANTES mRNA could be detected in the spleen cells from naïve animals stimulated with LPS or PMA plus ionomycin, the levels were significantly enhanced after BCG vaccination. mRNA expression was also elevated in macrophages infected with live mycobacteria after BCG vaccination. However, macrophages infected with the virulent H37Rv strain of M. tuberculosis showed 75 to 90% reductions in IL-1␤ expression and 25 to 60% reductions in RANTES mRNA expression compared with macrophages infected with the attenuated H37Ra strain. The IL-1␤ mRNA levels peaked as soon as 1 h after PPD stimulation and 4 h after M. tuberculosis H37Rv infection of macrophages. In contrast, RANTES mRNA expression was delayed until 48 h after infection. These results indicate that molecular mediators produced in response to various stimuli associated with protective immunity against mycobacteria are upregulated after BCG vaccination; however, a significantly weaker response was observed with virulent M. tuberculosis. These initial studies indicate that BCG vaccination has a positive effect on IL-1␤ and RANTES mRNA expression by host cells in a highly relevant animal tuberculosis model.