Human intestinal mucosa alters T-cell reactivities

Area of Science:

• Immunology
• Gastrointestinal Biology

Background:

• T lymphocytes in peripheral blood exhibit distinct functional properties compared to those in the lamina propria.
• Lamina propria T lymphocytes show reduced proliferation to T-cell receptor/CD3 and protein kinase C stimulation, but enhanced reactivity to CD2/CD28.
• Intestinal mucosa supernatant mimics the functional state of lamina propria T lymphocytes when cocultured with peripheral T cells.

Purpose of the Study:

• To identify and characterize the substances within mucosal supernatant responsible for suppressing T-cell receptor-dependent signaling.
• To elucidate the molecular nature of these inhibitory factors in the intestinal environment.

Main Methods:

• Production and preparation of mucosal supernatant.
• Dialysis of supernatant using membranes with specific pore sizes (12,000-14,000 Da).
• Enzymatic digestion with proteinase K and reduction with agents like 2-mercaptoethanol and dithiothreitol.
• Assay of supernatant activity on peripheral blood T lymphocyte proliferation.

Main Results:

• Dialysis indicated the active substances are smaller than 12,000-14,000 Da.
• Proteinase K digestion did not abolish the inhibitory activity, suggesting non-protein/non-peptide nature.
• The inhibitory effects were reversible by reducing agents, pointing to oxidative properties of the substances.

Conclusions:

• Mucosal substances that down-regulate antigen receptor-induced T lymphocyte proliferation are identified as small, non-protein, non-peptide molecules.
• These molecules possess oxidative properties and play a role in modulating immune responses within the intestinal mucosa.