Macrophage-agglutinating factor produced in vitro by BCG-sensitized lymphocytes

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• BCG-sensitization induces delayed hypersensitivity reactions.
• Lung lavage fluids contain factors affecting macrophage behavior.
• Alveolar macrophages play a key role in pulmonary immune responses.

Purpose of the Study:

• To identify and characterize a factor responsible for macrophage agglutination in BCG-sensitized rabbits.
• To investigate the cellular origin and synthesis of this factor.
• To differentiate this factor from known immune mediators like migration inhibition factor.

Main Methods:

• Cell culture of BCG-sensitized rabbit lymph node and spleen cells.
• Macrophage agglutination assays.
• Inhibition studies using puromycin and actinomycin D.
• Purification of lymphocytes and macrophages.
• Gel filtration chromatography (Sephadex G-100, Ultrogel AcA-34).

Main Results:

• Supernatant fluids from sensitized cells contained a potent macrophage-agglutinating factor (MAgF).
• MAgF production by lymph node cells suggested active synthesis, while spleen cells showed release kinetics.
• Lymphocytes were identified as the primary producers of MAgF.
• MAgF was separated from migration inhibition factor and indicated a high molecular weight (>400,000).

Conclusions:

• A novel macrophage-agglutinating factor (MAgF) is produced by lymphocytes in BCG-sensitized rabbits.
• MAgF exhibits distinct properties from migration inhibition factor.
• MAgF may contribute to macrophage adherence during granuloma formation in vivo.