CD44 cross-linking induces protein kinase C-regulated migration of human T lymphocytes.

The cell surface receptor CD44 is widely implicated in leukocyte migration to inflammatory sites. In this study, the responses of human T cells following cross-linking of CD44 were examined. We demonstrate that engagement of CD44 using immobilized mAbs or hyaluronan-enriched extracellular matrix lattices induces active migration in T lymphocytes accompanied by cycles of cytoskeletal rearrangement and cell polarization. We have investigated the functional impact and subcellular localization of protein kinase C (PKC) isoenzymes, beta and delta, previously shown by our group to be involved in active T cell locomotion induced by leukocyte function-associated antigen-1 (LFA-1) integrin receptors. PKCbeta was associated with the centrosome and the microtubule-rich tail of the polarized cell and PKCdelta was predominantly located about the region of the microtubule organizing center. A selective pharmacological inhibitor of classical PKC isoforms, Go6976, suppressed lymphocyte polarization and migration following CD44 ligation. Selective targeting of PKCdelta using the pharmacological inhibitor rottlerin or a pseudosubstrate-blocking peptide reduced CD44-activated cell migration but did not completely ablate it. Our data demonstrate that ligation of CD44 induces phenotypic changes, cytoskeletal rearrangements and redistribution of PKC isoforms beta and delta, resulting in cell migration, as previously described for the cell surface receptor, LFA-1. This suggests potential convergence of intracellular signaling pathways induced via CD44 and LFA-1 integrin.