Triggering through CD16 or phorbol esters enhances adhesion of NK cells to laminin via very late antigen 6

Gismondi et al . tion (19) (20) (21) . Our results suggest that VLA-6 and CD16 are coupled by intracellular signaling pathways, i.e., CD16 triggers a cascade of biochemical events or second messenger production that lead to increased VLA6 adhesive function. The rapid enhancement of NK cell adhesion to LM upon activation occurs without changes in the levels of cell surface expression of VLA6 and the other (31 LMR (data not shown), as previously described for activated T lymphocytes (10), suggesting that a qualitative alteration of integrin is more likely responsible for enhanced adhesiveness . In an attempt to elucidate the biochemical changes occurring after CD16-or TPA-induced cell activation, we observed an increase in the phosphorylation status of a6 . a6 phosphorylation is already evident after 5 min of stimulation and declines differently depending on the activating agent . Indeed, TPAinduced phosphorylation persists for at least 20 min whereas that induced by CD16 declines after 10 min of stimulation . Constitutive low levels of a6 phosphorylation were observed, suggesting that NK cell activation may quantitatively rather than qualitatively affect c16 phosphorylation status. In these experimental conditions, no phosphorylation of (31 subunit was observed.