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

Activation-dependent Adhesion to LM Correlates with Changes in the Phosphorylation Status ofa6 Subunit. We have analyzed whether stimulation of NK cells with TPA or anti-CD16 mAb could induce changes in the phosphorylation status of VLA-6 . 32P-labeled NK cells were stimulated with TPA or anti-CD16 mAb for different times (5-20 min), and cell extracts were immunoprecipitated with anti-c16 or anti-,131 antibodies and analyzed by SDS-PAGE under nonreducing conditions . Both TPA and anti-CD16 (Fig. 8 A) , but not anti-CD56 (Fig . 8 B) phorylation was already observed at 5 min and persisted until 20 min after stimulation, whereas that induced by CD16 engagement declined after 10 min. Low levels of u6 phosphoprotein were present in untreated controls. In these experimental conditions, no phosphorylation of u6-associated (31 subunit was observed.