Recombinant guinea pig TNF-alpha enhances antigen-specific type 1 T lymphocyte activation in guinea pig splenocytes

TNF-alpha is a principal pro-inflammatory cytokine which contributes to the activation of innate immunity and the transition to antigen-specific adaptive immunity in tuberculosis. Using recombinant guinea pig (rgp) TNF-alpha, the effect of TNF-alpha on lymphocyte activation was examined in unvaccinated and BCG-vaccinated guinea pigs. Splenocytes were stimulated with PPD or ConA, in the presence or absence of rgp TNF-alpha for 96 h. Lymphocyte proliferation was measured using [(3)H]thymidine uptake, and IL-12 p40 and IFN-gamma mRNA were analyzed using real-time PCR. rgpTNF-alpha alone was able to stimulate a significant degree of proliferation in splenocytes. The addition of rgpTNF-alpha to PPD-stimulated cells enhanced the proliferation of splenocytes from BCG-vaccinated guinea pigs. Furthermore, enhancement of proliferation by rgpTNF-alpha was found to be correlated with upregulation of the levels of Type 1 cytokine mRNA (IL-12p40 and IFN-gamma) in splenocyte cultures. This suggests that TNF-alpha plays an important role in the regulation of Type 1 T cell-mediated immune responses in the guinea pig.