Effects of migration inhibiting factor(s) on the in vitro detachment of macrophages

Area of Science:

• Immunology
• Cell Biology

Background:

• Bacillus Calmette-Guérin (BCG) is an immunotherapy agent.
• Purified protein derivative (PPD) is a mixture of proteins derived from Mycobacterium tuberculosis.
• Macrophage migration is a key process in immune responses.

Purpose of the Study:

• To investigate the effect of supernatants from BCG-sensitized mouse spleen cells on macrophage migration and adhesion.
• To evaluate a novel assay for measuring macrophage migration inhibitory factor (MIF) activity.

Main Methods:

• Spleen cells from BCG-injected mice were cultured with PPD.
• Supernatants were collected and tested for their effect on normal mouse peritoneal macrophage migration.
• A novel test system assessed the effect of supernatants on the detachment of adherent macrophages.
• Supernatants were treated with neuraminidase, chymotrypsin, and heat to assess the nature of inhibitory activity.

Main Results:

• Supernatants specifically inhibited macrophage migration compared to controls.
• Supernatants decreased the detachment of adherent macrophages in the novel test system.
• Both migration and detachment inhibitory activities were abolished by neuraminidase and chymotrypsin.
• The inhibitory activities were thermostable.

Conclusions:

• The study demonstrates that supernatants from BCG-sensitized mice possess macrophage migration inhibitory activity.
• A novel detachment assay appears to be a sensitive indicator of MIF activity.
• The inhibitory factor is likely proteinaceous in nature, sensitive to enzymatic degradation but thermostable.