Changes in natural killer cell subsets in pediatric liver transplant recipients.

NK cells are important in the immune response against tumors and virally infected cells. A balance between inhibitory and activating receptors controls the effector functions of NK cells. We examined the fate of circulating NK cells and the expression of the NK cell-activating receptors in pediatric liver transplant recipients. Blood specimens were collected from 38 pediatric liver transplant recipients before transplant, and at one wk, one, three, six, and nine months, and one yr post-transplant. PBMCs were isolated and analyzed for the levels of NK cell activation receptors NKp30, NKp46, and NKG2D in the CD56(dim) CD16(+) and CD56(bright) CD16(+/-) subsets of NK cells. We demonstrated that there is a significant decrease in the percentage of circulating NK cells post-transplant (pretransplant 7.69 ± 1.54 vs. one wk post-transplant 1.73 ± 0.44) in pediatric liver transplant recipients. Interestingly, NKp30 expression is significantly increased, while NKp46 and NKG2D levels remain stable on the NK cells that persist at one wk post-transplant. These data indicate that the numbers and subsets of circulating NK cells are altered in children after liver transplantation.

Identification of the rat NKG2D ligands, RAE1L and RRLT, and their role in allograft rejection.

NKG2D is a receptor expressed by NK cells and subsets of T lymphocytes. On NK cells, NKG2D functions as a stimulatory receptor that induces effector functions. We cloned and expressed two rat NKG2D ligands, both members of the RAE1 family, RAE1L and RRLT, and demonstrate that these ligands can induce IFN-gamma secretion and cytotoxicity by rat NK cells. To examine changes in expression of NKG2D and the NKG2D ligands RAE1L and RRLT after transplantation, we used a Dark Agouti (DA)-->Lewis rat model of liver transplantation. NKG2D expression was significantly increased in allogeneic liver grafts by day 7 post-transplant. Ligands of NKG2D, absent in normal liver, were readily detected in both syngeneic and allogeneic liver grafts by day 1 post-transplant. By day 7 post-transplant, hepatocyte RAE1L and RRLT expression was significantly and specifically increased in liver allografts. In contrast to acute rejection that develops in the DA-->Lewis model, transplantation of Lewis livers into DA recipients (Lewis-->DA) results in spontaneous tolerance. Interestingly, expression of RAE1L and RRLT is low in Lewis-->DA liver allografts, but significantly increased in DA-->Lewis liver allografts undergoing rejection. In conclusion, our results suggest that expression of NKG2D ligands may be important in allograft rejection.

Efficacy and Safety of the Absorb Bioresorbable Vascular Scaffold in Females and Males: Results of an Individual Patient-Level Pooled Meta-Analysis of Randomized Controlled Trials.

OBJECTIVES: Because females are under-represented in coronary trials, this study sought to assess the relative safety and efficacy of Absorb bioresorbable vascular scaffold (BVS) (Abbott Vascular, Santa Clara, California) and the Xience everolimus-eluting stent in females compared with males. BACKGROUND: The Absorb everolimus-eluting BVS provides drug delivery and mechanical support similar to a metallic drug-eluting stent, followed by resorption and restoration of more normal vascular structure with the potential to improve late clinical outcomes. METHODS: The ABSORB II, ABSORB III, ABSORB Japan, and ABSORB China trials were pooled. Baseline clinical, angiography, procedural variables, and 2-year outcomes were analyzed by sex and device. RESULTS: Among 3,384 randomized patients, 932 (27.5%) were female. Females were older, more often had diabetes and hypertension, but had less everolimus-eluting stent, 3-vessel disease, and smoking compared with males (all p≤0.001). The 2-year rates of target lesion failure with BVS versus everolimus-eluting stent in females were 8.9% versus 6.2% (study-level adjusted hazard ratio: 1.47; 95% confidence interval [CI]: 0.88 to 2.46) and 8.9% versus 6.4% in males (HR: 1.40; 95% CI: 1.02 to 1.92; pinteraction = 0.85). There were no significant interactions between sex and device type for any of the components of target lesion failure. CONCLUSIONS: The relative treatment effects of BVS and everolimus-eluting stent for the 2-year rates of target lesion failure and other cardiovascular outcomes were consistent in females and males.