Mitogen stimulation promotes human T lymphocyte adhesion to fibronectin

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• T lymphocytes play crucial roles in immune responses.
• Cell adhesion molecules mediate interactions between lymphocytes and their environment.
• Fibronectin (Fn) is an extracellular matrix protein involved in cell adhesion and migration.

Purpose of the Study:

• To investigate the adhesion of human T lymphocytes to plasma fibronectin (pFn).
• To determine the effect of T cell activation on pFn adhesion.
• To elucidate the mechanism of T cell-Fn interaction.

Main Methods:

• Adhesion assays using purified human peripheral blood T lymphocytes and fibronectin-coated surfaces.
• Inhibition studies using a synthetic peptide (Arg-Gly-Asp-Ser).
• T cell activation using concanavalin A (Con A) and 12-O-tetradecanoyl-phorbol-13-acetate (TPA).
• Analysis of cell spreading and F-actin organization.
• Overlay assay to identify pFn-binding molecules on T cells.

Main Results:

• T lymphocytes adhered to fibronectin but not to laminin or type I collagen.
• Adhesion to pFn was inhibited by Arg-Gly-Asp-Ser peptide.
• Activated T cells showed significantly higher adherence to pFn compared to resting cells.
• Activated T cells spread on pFn and exhibited altered F-actin organization.
• A 190,000 Mr polypeptide on activated T cells bound to pFn, suggesting a receptor-mediated interaction.

Conclusions:

• T lymphocyte adhesion to fibronectin is specific and can be modulated by activation.
• T cell activation enhances fibronectin binding and promotes cell spreading, indicating a dynamic interaction.
• Fibronectin adhesion may involve a two-stage process: initial binding followed by active spreading, potentially mediated by altered interactions between fibronectin receptors and the actin cytoskeleton.