CELLULAR REACTIONS TO DEFATTED TUBERCLE BACILLI AND THEIR PRODUCTS

Area of Science:

• Immunology
• Microbiology
• Cell Biology

Background:

• Cellular responses to tubercle bacilli are intricate.
• Defatted tubercle bacilli exhibit complex immunological characteristics.
• Heat-killed whole tubercle bacilli induce similar complex reactions.

Purpose of the Study:

• To investigate the specific cellular reactions elicited by defatted tubercle bacilli.
• To differentiate the immunological roles of lipid and polysaccharide components of tubercle bacilli.
• To understand the mechanisms behind foreign body giant cell formation and eosinophil/neutrophil recruitment.

Main Methods:

• Isolation and fractionation of lipids from defatted tubercle bacilli.
• Analysis of acid-fast and non-acid-fast properties of isolated components.
• Histological examination of tissue reactions, including cell infiltration (eosinophils, neutrophiles) and giant cell formation.

Main Results:

• The firmly bound lipid from defatted bacilli is non-acid-fast.
• An acid-fast hydroxy acid and a non-acid-fast polysaccharide were identified within the lipid.
• The hydroxy acid induced foreign body giant cells and eosinophil infiltration.
• Polysaccharides stimulated neutrophile recruitment.

Conclusions:

• The cellular reactions to defatted tubercle bacilli are mediated by their distinct lipid and polysaccharide constituents.
• The acid-fast hydroxy acid is a key component in inducing granulomatous inflammation and eosinophilia.
• Polysaccharides play a role in neutrophile chemotaxis in response to tubercle bacilli.