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Inhibition of macrophage migration by normal guinea pig intestinal secretions
Abstract:
The incubation fluid from 24-hr cultures of normal guinea pig small intestines was found to contain activity capable of inhibiting the migration of normal guinea pig peritoneal macrophages. Each of three different culture fluids showed macrophage inhibitory activity in the 25,000-55,000 mol wt range when subjected to Sephadex G-100 gel filtration. One of these three preparations also contained inhibitory activity in the excluded volume. The low molecular weight activity was nondialyzable and heat stable to 56 degrees for 30 min. It was destroyed by boiling for 1 hr, and its activity was reversed by 10(-4)M epinephrine. Based upon these properties it is suggested that this activity was due to migration inhibitory factor (MIF). The high molecular weight inhibitor was stable to heating and its activity was not reversed by epinephrine. This material was most likely endotoxin. The presence of MIF, which may be associated with T-cell activity in the intestine, suggests that cell-mediated immunity (CMI) could play a role in local protection against gut infections. Furthermore, its presence in normal intestinal secretions suggests that some MIF-producing cells are always being stimulated by normal flora. The question is thus raised whether further specific stimulation of local CMI in the gut could be successful.
Insights
Normal guinea pig intestines secrete migration inhibitory factor (MIF), a key component of cell-mediated immunity (CMI). This finding suggests CMI plays a role in gut protection and may be stimulated by normal gut flora.
Area of Science:
- Immunology
- Gastroenterology
Background:
- The small intestine's immune functions are crucial for gut health.
- Cell-mediated immunity (CMI) is vital for local protection against infections.
Purpose of the Study:
- To investigate the presence and characteristics of macrophage migration inhibitory activity in normal guinea pig intestinal secretions.
- To explore the potential role of CMI in the normal gut environment.
Main Methods:
- Incubation of normal guinea pig small intestinal tissues.
- Macrophage migration inhibition assays.
- Sephadex G-100 gel filtration to determine molecular weight of inhibitory substances.
- Heat stability and epinephrine reversal tests.
Main Results:
- Intestinal incubation fluid inhibited guinea pig peritoneal macrophage migration.
- Macrophage inhibitory activity was identified in two molecular weight ranges: 25,000-55,000 (low MW) and excluded volume (high MW).
- Low MW activity exhibited properties consistent with migration inhibitory factor (MIF), being heat-stable and epinephrine-reversible. High MW activity was likely endotoxin.
Conclusions:
- Normal guinea pig intestinal secretions contain MIF, suggesting CMI is active in the gut.
- The presence of MIF indicates that cells producing it are stimulated by normal gut flora.
- These findings raise questions about the potential for enhancing local gut CMI for infection control.