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Haptotactic activity of fibronectin on lymphocyte migration in vitro
J M Davis1, J St John, H T Cheung
1Department of Biological Sciences, Illinois State University, Normal 61761.
Insights
Fibronectin (FN) guides lymphocyte migration via haptotaxis, not chemotaxis or chemokinesis. Specific FN domains differentially affect spleen and thymus lymphocyte migration, with excessive binding hindering movement.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Fibronectin (FN) is known to influence cell adhesion and migration.
- The specific role of fibronectin in lymphocyte migration remains largely uncharacterized.
- Understanding lymphocyte migration is crucial for immune response and disease processes.
Purpose of the Study:
- To investigate the effects of fibronectin on the in vitro migration of lymphocytes.
- To determine if fibronectin exhibits chemotactic, chemokinetic, or haptotactic activity on lymphocytes.
- To elucidate the role of specific fibronectin domains in lymphocyte migration.
Main Methods:
- Utilized checkerboard analysis within a blind-well microchemotaxis assay.
- Assessed lymphocyte migration towards soluble and substrate-bound fibronectin.
- Examined the haptotactic potential of fibronectin's cell-binding and heparin-binding domains.
Main Results:
- Soluble fibronectin demonstrated no chemotactic or chemokinetic effects on spleen or thymus lymphocytes.
- Unidirectional fibronectin coating enhanced lymphocyte migration, indicating haptotaxis.
- The cell-binding domain was haptotactic for both lymphocyte types; the heparin-binding domain was haptotactic only for spleen lymphocytes, potentially due to excessive binding in thymus lymphocytes.
Conclusions:
- Fibronectin mediates lymphocyte migration through haptotaxis, not chemotaxis or chemokinesis.
- Lymphocyte migration is influenced by specific fibronectin domains and their binding affinities.
- Excessive binding to the heparin-binding domain can impede thymus lymphocyte motility.
Abstract:
In addition to mediating cell adhesion, fibronectin (FN) also affects the migration of different cell types. However, the role of FN in lymphocyte migration is unclear. In this study, we examined the effects of FN on the in vitro migration of lymphocytes. Using the checkerboard analysis in a blind-well microchemotaxis assay, soluble FN was determined to have neither a chemotactic nor chemokinetic effect on spleen or thymus lymphocytes. However, when the nitrocellulose filter was coated unidirectionally with FN, the migration of both spleen and thymus lymphocytes into the filter was enhanced, indicating that FN is haptotactic for lymphocytes. When the filter was coated bidirectionally, no enhancement in migration was observed, indicating that FN is not haptokinetic for lymphocytes. When the FN cell-binding domain and the heparin-binding domain were tested, the cell-binding domain was haptotactic for both spleen and thymus lymphocytes, whereas the heparin-binding domain was only haptotactic for spleen lymphocytes. Because the heparin-binding domain can mediate strong adhesion of thymus lymphocytes, the lack of haptotactic activity is likely to be the result of excessive binding that prevents cell motility.