T Lymphocyte Receptor-Ligand Interactions for Migration on Microcontact Printed Intracellular Adhesion Molecule-(ICAM)-1 Surfaces

Abstract

Recruitment of T lymphocytes into lymphoid organs and peripheral tissues during immune surveillance and inflammation is dependent upon a tightly regulated multistep adhesion cascade. Upon endothelium exposure to certain cytokines, cell adhesion molecules are upregulated providing a means for T lymphocytes to tether, roll, adhere, and migrate. Upon binding of the integrin lymphocyte function-associated antigen 1 (LFA-1) to the ligand, intracellular adhesion molecule 1 (ICAM-1), “outside-in” signaling is primed to induce firm adhesion and migration. Here, through the use of microcontact printing (μCP) we have studied the random motility of human peripheral T lymphocytes and the effects of the homeostatic chemokines CCL19, CCL21, and CXCL12 on ICAM-1 coated surfaces. Studies have demonstrated that the LFA-1/ICAM-1 “outside-in” signaling is in concert with the “inside-out” signals produced downstream from chemokine binding to promote chemokinesis. The random motility coefficient (μ) on ICAM-1 surfaces was found to be 200.37 ± 13.30 μm2/min. Unexpectedly, the random motility coefficient had no significant differences between chemokine concentrations even around the KD of the receptors CCR7 and CXCR4. We hypothesize that the “outside-in” signaling dictated by LFA-1/ICAM-1 binding overwhelms the “inside-out” signaling from the chemokines preventing a difference in the random motility coefficient to be observed. In addition, microcontact printing will permit us to pattern ICAM-1 to observe T lymphocytes on controlled substrates. Furthermore, through the use of a microfluidic device we can begin to elucidate the effects of chemokine gradients on directed T lymphocyte migration. By producing single and competing chemokine gradients, we can calculate the chemotactic index to assess the potency of these chemokines on chemotaxis.