BCG vaccination of guinea pigs modulates Mycobacterium tuberculosis-induced CCL5 (RANTES) production in vitro and in vivo

CCL5 can attract and activate macrophages and Th1 lymphocytes, which are involved in eliciting a protective immune response against tuberculosis. In this study, the effects of BCG vaccination on CCL5 production in vitro and in vivo in the guinea pig model were examined. Splenocytes, alveolar, and resident peritoneal macrophages obtained from naive and BCG-vaccinated animals were infected with Mycobacterium tuberculosis in vitro at various time points and analyzed for CCL5 mRNA and protein levels. All three leukocyte populations harvested from BCG-vaccinated guinea pigs and infected with M. tuberculosis produced elevated CCL5 mRNA and protein compared to infected cells from naive animals. The kinetics of CCL5 production in vivo was evaluated by inducing tuberculous pleurisy in BCG-vaccinated guinea pigs and analyzing CCL5 in pleural effusions at daily intervals. Both CCL5 mRNA and protein levels increased to maximum levels at day 4 post-pleurisy induction. These data suggest that BCG-vaccination enhances CCL5 production in vitro and in vivo. The effect of neutralizing CCL5 with polyclonal anti-CCL5 IgG in vivo during tuberculous pleurisy resulted in a trend toward diminished levels of pro-inflammatory cytokine mRNA, although neutralizing CCL5 in vivo did not appear to alter the intensity of the histopathological response.