Mycobacterial infection primes T cells and macrophages for enhanced recruitment of neutrophils.

C57BL/6 mice intraperitoneally infected with Mycobacterium bovis BCG (substrain Pasteur) recruited significantly higher numbers of neutrophils after an intraperitoneal inoculation of either BCG protein antigen or of endotoxin than uninfected control mice. Antigen-induced neutrophil recruitment was mediated by T cells of both CD4+ and CD8+ phenotype and was also observed in the C5-deficient DBA/2 mouse strain. The adoptive transfer of immune serum did not prime mice for enhanced antigen-mediated recruitment of neutrophils. The endotoxin-mediated recruitment of neutrophils was also enhanced in infected as compared to uninfected DBA/2 mice. Finally, endotoxin-pulsed purified macrophages from infected C57BL/6 mice recruited higher numbers of neutrophils than endotoxin-pulsed macrophages from normal mice in an adoptive transfer to peritoneal cavities of naive recipient mice. These data show that during mycobacterial infection, T cells and macrophages are primed for recruitment of neutrophils after being triggered in specific or nonspecific ways. This may represent a means to cope with secondary infections by allowing for extensive neutrophil infiltration readily upon microbial challenge.