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

Area of Science:

• Immunology
• Microbiology
• Infectious Diseases

Background:

• Mycobacterium bovis BCG infection in C57BL/6 mice leads to enhanced neutrophil recruitment.
• This heightened response occurs following intraperitoneal inoculation with BCG protein antigen or endotoxin.

Purpose of the Study:

• To investigate the cellular mechanisms underlying T cell- and macrophage-mediated neutrophil recruitment during mycobacterial infection.
• To determine if primed immune cells contribute to host defense against secondary infections.

Main Methods:

• Intraperitoneal infection of C57BL/6 mice with Mycobacterium bovis BCG.
• Analysis of neutrophil recruitment following antigen or endotoxin challenge.
• Adoptive transfer experiments using immune serum, T cells, and macrophages.
• Studies in C5-deficient DBA/2 mice to assess complement-independent mechanisms.

Main Results:

• Antigen-induced neutrophil recruitment was mediated by CD4+ and CD8+ T cells and occurred in C5-deficient mice.
• Endotoxin-mediated neutrophil recruitment was enhanced in infected mice, including DBA/2 mice.
• Macrophages from infected mice, when pulsed with endotoxin, showed enhanced neutrophil recruitment capacity.

Conclusions:

• Mycobacterial infection primes T cells and macrophages to enhance neutrophil recruitment in response to specific or non-specific stimuli.
• This primed immune response may serve as a crucial mechanism for managing secondary infections through rapid neutrophil infiltration.