Delta-Short Consensus Repeat 4-Decay Accelerating Factor (DAF: CD55) Inhibits Complement-Mediated Cytolysis but Not NK Cell-Mediated Cytolysis

Abstract

NK cells play a critical role in the rejection of xenografts. In this study, we report on an investigation of the effect of complement regulatory protein, a decay accelerating factor (DAF: CD55), in particular, on NK cell-mediated cytolysis. Amelioration of human NK cell-mediated pig endothelial cell (PEC) and pig fibroblast cell lyses by various deletion mutants and point substitutions of DAF was tested, and compared with their complement regulatory function. Although wild-type DAF and the delta-short consensus repeat (SCR) 1-DAF showed clear inhibition of both complement-mediated and NK-mediated PEC lyses, delta-SCR2-DAF and delta-SCR3-DAF failed to suppress either process. However, delta-SCR4-DAF showed a clear complement regulatory effect, but had no effect on NK cells. Conversely, the point substitution of DAF (L147·F148 to SS and KKK125–127 to TTT) was half down-regulated in complement inhibitory function, but the inhibition of NK-mediated PEC lysis remained unchanged. Other complement regulatory proteins, such as the cell membrane-bound form factor H, fH-PI, and C1-inactivator, C1-INH-PI, and CD59 were also assessed, but no suppressive effect on NK cell-mediated PEC lysis was found. These data suggest, for DAF to function on NK cells, SCR2–4 is required but no relation to its complement regulatory function exists.

Expression Profiling of Murine Double-Negative Regulatory T Cells Suggest Mechanisms for Prolonged Cardiac Allograft Survival

“…We found that DN Treg cells overexpressed CD55 and VEGF, whereas mutant clones did not show significant increases in expression of any survival genes. It has been demonstrated that CD55 prevents cell death through complement activation (57,58), whereas VEGF has been implicated in cell proliferation (59,60). This supports the observation that DN Treg cells are highly resistant to activation induced cell death (55,56).…”

Virion-Associated Complement Regulator CD55 Is More Potent than CD46 in Mediating Resistance of Mumps Virus and Vesicular Stomatitis Virus to Neutralization

“…CHO cells stably expressing CD55 (CHO-CD55) were derived by transfecting CHO or CHO-CD46 cells with a plasmid encoding CD55 (kindly provided by Shuji Miyagawa [28,33]), followed by selection for resistance to 100 g/ml G418 or both G418 and hygromycin (for CHO-CD46/55 cells). The Enders strain of MuV (ATCC VR-1379) and Orsay strain of VSV were grown in CHO cells supplemented with 2% heat-inactivated (HI) serum.…”

Multi‐transgenic pigs for xenotransplantation

“…Although CD55 is involved in the innate immune system and upregulates NK cell activity in response to bacterial pathogen activity (Tieng et al, 2002), it is able to inhibit NK cell-mediated lysis. Miyagawa et al, (2004) checked different CD55 deletion mutants and observed that wild type and delta-SCR1 are able to inhibit complement-mediated and NKmediated lysis of porcine cells. Delta-SCR2 and delta SCR3 mutants could not suppress lysis, whereas delta-SCR4 mutants could suppress complementmediated lysis but not NK cell-mediated lysis.…”

“…The SCR1 domain cannot be used by pathogens as a receptor (Lindahl et al, 2000) and the delta-SCR1 mutant has the same capacity to inhibit complement-mediated as well as NK-cell mediated cell lysis (Miyagawa et al, 2004). Moreover, the SCR1 mediated CD55-CD97 interactions, causing a CD4 + T cell activation would be avoided (Capasso et al, 2006).…”

“…The 1706 multi-transgene combination should also have protective effects at these levels. High CD55 expression levels have already been shown to inhibit NK cell activation (Miyagawa et al, 2004). CD46 expression has significant effects on inhibition of procoagulant and antifibrinolytic pathways (Bongoni et al, 2015) and a combination of GGTA1 knockout and CD46 expression was shown to down-regulate the human T-cell response to porcine cells (Ezzelarab et al, 2011;Wilhite et al, 2012).…”