4E). To evaluate the role of CD39 in NK cells, adoptive transfer of sorted NK cells from CD39-null and IFNγ null mice into Rag2/common gamma-null mice (deficient of T cells, B cells, and NK cells) was performed (Fig. 4F). ALT plasma levels used as a parameter of liver injury were significantly decreased in the absence of NK cells, as assessed in Rag2/common gamma-null mice without prior adoptive transfer (designated as control) compared to the same mice after transfer of wild-type NK cells. Hepatic injury was substantially decreased after transfer

of NK cells from IFNγ-null (Fig. 4E) or of CD39-null NK (Fig. 4F) animals after reperfusion. Differences in expression pattern for CD27 and KLRG1 as demonstrated in quiescent cells in vitro were further assessed in vivo (Fig. 5A,B). Hepatic NK cells were purified from control and mutant mice under basal conditions as well as after IRI. Significantly decreased levels of CD27-positive cells were observed in CD39-null VX-809 research buy mice prior

to ischemic injury. After IRI, numbers of CD27-positive NK cells significantly decreased in both wild-type and mutant mice. Conversely, levels of KLRG1-positive cells appeared increased in mutant mice under basal conditions as well as after IRI. Splenic NK cells were isolated from wild-type mice. To evaluate the role of P2 receptors in regulating the secretion of IFNγ, NK cells were stimulated with the cytokines IL-12 and IL-18 in the presence or absence of extracellular nucleotides. These two selected cytokines are potent activators ABT-888 research buy of NK cells and have been shown to be associated with hepatic IRI.4, 23, 24 Although the secretion of IFNγ was unaffected by ATP (not shown), this was significantly decreased in response to nonhydrolyzable nucleotides ATPγS and ADPβS; this occurred in a dose-dependent manner (Fig. 6A,B). No inhibition of IFNγ secretion

was observed in response to uridine triphosphate gamma S (UTPγS; data not shown). In order to exclude toxic effects of extracellular nucleotides in vitro, cell viability was assessed using an MTT assay (Fig. 6C). In the presence of increasing concentrations of ATPγS, viability in fact increased. Interestingly, this effect occurred in direct response to exposure of cells to ATPγS or UTPγS and it was independent of exposure to IL-12 find more and/or IL-18 (not shown). Comparisons of wild-type NK cells versus CD39-null NK cells demonstrated decreased levels of IFNγ secretion in the mutant mice (Fig. 6D). This effect was independent of the increasing concentrations of ATPγS. During partial hepatic IRI, the functional expression of CD39 alters levels of extracellular nucleotides and influences the generation of adenosine, thus affecting tissue injury and survival outcomes. The extent of injury in this model, as assessed by elevation of ALT levels and the degree of hepatic necrosis, is substantially decreased in mice null for CD39 when compared to wild-type mice.