Myosin-IIA and ICAM-1 Regulate the Interchange between Two Distinct Modes of T Cell Migration

How T cells achieve rapid chemotactic motility tinder certain circumstances and efficient cell surface surveillance in others is not fully understood. We show that T lymphocytes are motile in two distinct modes: a fast amoeboid-like mode, which uses sequential discontinuous contacts to the substrate; and a slower mode using a single continuously translating adhesion, similar to mesenchymal motility. Myosin-IIA is necessary for fast amoeboid motility, and our data suggests that this occurs via cyclical rear-mediated compressions that eliminate existing adhesions while licensing subsequent ones at the front of the cell. Regulation of Myosin-IIA function in T cells is thus a key mechanism to regulate surface contact area and crawling velocity within different environments. This can provide T lymphocytes with motile and adhesive properties that are uniquely suited toward alternative requirements for immune surveillance and response. The Journal of Immunology, 2009, 182: 2041-2050.