Growth of Brucella abortus in macrophages from resistant and susceptible mouse strains

C57Bl/10 mice have a superior ability to control chronic infections with vi rulent strains of the intracellular bacteria Brucella abortus compared with BALB/c mice. While a number of differences in the cytokines produced by ly mphocytes following infection of these two strains of mice have been shown, macrophages have not been evaluated for their role in conveying relative r esistance. The importance of macrophages in control of brucella infections is demonstrated by the observations that intracellular survival of various strains of B. abortus directly correlates with their virulence in vivo, and the ability of macrophages to control brucellae in vitro has been shown to correlate with a brucella-resistant phenotype in ruminants. While both BAL B/c and C57Bl are Nramp-susceptible mouse strains, additional differences i n macrophage function outside of the Nramp1 gene effects could influence su sceptibility to brucellosis. The studies conducted here comparing the abili ty of macrophages from C57Bl/10 and BALB/c mice indicate that the macrophag es from resistant mice did not control intracellular growth of B. abortus s train 2308 more efficiently than those from the susceptible mice, either in the absence of, or following, interferon-gamma activation or iron suppleme ntation. A number of different conditions for culturing macrophages were ev aluated to rule out the influence of antibiotics on the conclusions drawn f rom the results.