Opposite effects of M. leprae or M. bovis BCG delipidation on cellular accumulation into mouse pleural cavity. Distinct accomplishment of mycobacterial lipids in vivo.

OBJECTIVES AND

DESIGN

The effect of mycobacterial lipids on the onset of the early acute inflammatory response in BALB/c mice pleurisy was investigated.

MATERIALS AND

METHODS

Intact Mycobacterium leprae and Mycobacterium bovis BCG (BCG), their lipids, and delipidated mycobacteria were used to evaluate total leukocytes and cell types migrated to the pleural cavity (8 animals/experimental group).

RESULTS

BCG Moreau (x10(-6)/cavity), delipidated BCG and its lipids gradually recruited cells leading to arrival, respectively, of neutrophils (7.8+/-1.9, 4.7+/-0.9, 1.8+/-0.25) followed by mononuclear cells (4.8+/-0.8, 3.7+/-0.7, 2.45+/-0.22) and eosinophils (0.39+/-0.08, 0.32+/-0.11, 0.41+/-0.65). BCG delipidation decreased the number of migrated total leukocytes (ANOVA, and Newman-Keuls-Student-test), whereas M. leprae delipidation accumulated neutrophils (0.85+/-0.01) and eosinophils (1.65+/-0.18).

CONCLUSIONS

Intact M. leprae and its lipids did not incite any cell recruitment. Apolar external cell wall lipids from M. leprae and BCG induce different cellular responses. They seem to have a crucial importance at the first contact of mycobacteria with the host cell, modulating the influx of neutrophils/macrophages in the early (4/24 h) onset of the inflammatory reaction.