Growth of Mycobacterium avium in activated macrophages harvested from inbred mice with differing innate susceptibilities to mycobacterial infection

Abstract

The growth of Mycobacterium avium in macrophages obtained from Mycobacterium bovis BCG-infected mice was compared with that in macrophages from uninfected mice. BCG vaccination resulted in substantial macrophage activation, measured as increased acid phosphatase and superoxide anion production, as well as enhanced leishmanicidal activity. However, the activated macrophages were only able to reduce the rate of intracellular growth by Listeria monocytogenes and M. avium in vivo and did not express detectable levels of mycobactericidal activity in vitro. Exposure of the macrophage monolayers to concanavalin A-stimulated spleen cell supernatant fluid and lipopolysaccharide did not further enhance the ability of the BCG-activated macrophages to control the intracellular replication of the M. avium. Macrophages from BCG-infected C57BL/6 (BCG(S)) mice were quantitatively better able to control the intracellular replication of the M. avium challenge than were similar phagocytes obtained from BCG(r) (A/J) mice. These findings have important implications with respect to the expression of acquired resistance to these atypical mycobacterial infections.