[Neutrophil participation in early control and immune activation during experimental pulmonary tuberculosis]

Abstract

Background: Macrophages and neutrophils are professional phagocytes that participate in the control of mycobacterial infection.

Objective: We compared the pro-inflammatory cytokine production of both cell types during early pulmonary tuberculosis.

Material and methods: Balb/c mice were infected by intratracheal route with the H37Rv virulent strain, and bronchial washing cells were studied by cytofluorometry.

Results: A higher number of neutrophils with immunoreactivity against interleukin 1, interleukin 8 and tumor necrosis factor alpha were observed during the first week of infection. After, macrophages were the predominant cell type. In a second part of the study, infected mice were treated with the RB6-8C5 anti-neutrophil monoclonal antibody, and the course of the infection was observed. In comparison with controls, neutropenic mice showed higher bacillary loads in lungs and spleen, lower inflammatory infiltrate, smaller granulomas and lesser cutaneous delayed type hypersensitivity.

Conclusions: These results show that neutrophils are the most abundant inflammatory cell type during early murine pulmonary tuberculosis, and they participate in the lung bacilli clearance and prevention of blood dissemination. Neutrophils are also an important source of proinflammatory cytokines, contributing to the early recruitment and activation of macrophages and lymphocytes, favoring cell mediated immunity against mycobacterial infection.