Surfactant protein D delays Fas- and TRAIL-mediated extrinsic pathway of apoptosis in T cells

In this study we aimed to determine the effects of SP-D on Jurkat T cells and human T cells dying by apoptosis. Here we show that SP-D binds to Jurkat T cells and delays the progression of Fas (CD95)-Fas ligand and TRAIL –TRAIL receptor induced, but not TNF–TNF receptor-mediated apoptosis. SP-D exerts its effects by reducing the activation of initiator caspase-8 and executioner caspase-3. SP-D also delays the surface exposure of phosphatidylserine. The effect of SP-D was ablated by the presence of caspase-8 inhi bitor, but not by intrinsic pathway inhibitors. The binding ability of SP-D to dying cells decreases during the early stages of apoptosis, suggesting the release of apoptotic cell surface targets during apoptosis. SP-D also delays FasL-induced death of primary human T cells. SP-D delaying the progre ssion of the extrinsic pathway of apoptosis could have important implications in regulating immune cell homeostasis at mucosal surfaces.

Source: Apoptosis - February 5, 2017 Category: Molecular Biology Source Type: research