Effect of Substrate Ligand Presentation on the Motility of Human T-Lymphocytes

EFFECT OF SUBSTRATE LIGAND PRESENTATION ON THE MOTILITY OF HUMAN T-LYMPHOCYTES George Aaron Dominguez Daniel A. Hammer T lymphocyte homing and migration is critical for host defense and immunity. T lymphocytes must be captured from blood flow, tether and roll on the endothelial surface, engage chemokine receptors, and firmly adhere and migrate to sites of inflammation or to secondary lymphoid organs. How adhesive ligands, soluble factors such as chemokines, and fluid shear flow influence the motility of T lymphocytes is important for understanding this dynamic cascade of events. In this thesis, primary human T lymphocyte motility was quantified on various adhesive ligands (haptokinesis) in the presence of chemokines (chemokinesis) and in response to fluid flow. Through the use of microcontact printing onto PDMS surfaces we created surfaces that presented ligand at controlled densities either alone or in combination. The adhesive ligands ICAM-1, VCAM-1, and fibronectin were used to quantify cell migration in the absence of chemokine revealing different modes of T lymphocyte motility with ICAM-1 having an overall greater contribution. Using the homeostatic chemokines CCL19, CCL21, and CXCL12, we demonstrated that motility is biphasic and is dependent upon ICAM-1 concentration, and by presenting chemokines in combination, we can drive motility to higher levels than what was seen with each chemokine individually. Finally we demonstrated that directed migration either upstream or downstream of fluid flow is dependent upon the presence of ICAM-1, VCAM-1, or a combination of the two and the shear rate used. We have been able to show that adhesive ligands, chemokines, and shear flow all work in concert to promote robust primary human T lymphocyte adhesion and migration on microcontact printed PDMS surfaces. This research further elucidates how T lymphocytes interpret these signals for controlling homing to and motility within secondary lymphoid organs and the mechanisms of their migration.