The PlA2 polymorphism of the platelet glycoprotein IIIA gene as a risk factor for acute renal allograft rejection.

Glycoprotein IIIa/IIb is a membrane receptor for fibrinogen and von Willebrand factor that plays an important role in platelet aggregation. The beta integrin chain of this receptor, GPIIIa, is polymorphic, and the allele known as PlA2 has been associated with coronary thrombosis. The GPIIIa genotype of a cohort of 119 consecutive renal allograft recipients (46.3 +/- 13 yr; 85 M/34 F; 24.4% diabetic patients) was determined by PCR-restriction fragment length polymorphism, and those patients were followed for at least 12 mo. From 119 patients with at least 1 yr of follow-up, those who suffered an acute rejection (n = 52) showed a lower proportion of HLA-DR beta1 identity with the donor (7.7% versus 23.9%; P = 0.03), a higher proportion of cytomegalovirus-positive (CMV+) donors/CMV- recipients (21% versus 7.5%; P = 0.05), and the PlA2 allele was more frequent (48.1% versus 26.9%; P = 0.02) compared with patients free of acute rejection (n = 67). No other variable was associated with acute rejection in the univariate analysis. The impact of the three above-mentioned significant variables on acute rejection was analyzed by stepwise logistic regression. The presence of the PlA2 allele yielded an odds ratio of 2.75 (95% confidence interval, 1.01 to 7.93) and an HLA-DR beta1 identity of 0.2 (95% confidence interval, 0.06 to 0.99) for suffering an acute rejection episode. In addition, the serum creatinine at discharge was higher in PlA2-positive versus PlA2-negative patients (2.2 +/- 1.6 versus 1.5 +/- 0.6 mg/dl, respectively; P = 0.01), and the prevalence of proteinuria >1.5 g/d 1 yr after transplantation was significantly higher among patients showing the PlA2 allele (16% versus 3%; P = 0.02). Finally, in the entire cohort of patients, the 2-yr graft survival was significantly lower in PlA2-positive (n = 43) compared with PlA2-negative (n = 76) patients (85.7% versus 97.2%; P = 0.015). No differences were found in patient survival (95.2% versus 98.7%, respectively). Proportional hazards regression analysis (Cox regression model) confirmed that serum creatinine level at discharge is the best predictor of allograft survival, followed by CMV status, delayed graft function, and the glycoprotein IIIa/IIb genotype. The PlA2 polymorphism is an independent risk factor for acute renal graft rejection, affecting short-term graft survival. Future studies aimed at preventing the hemostatic imbalance favoring platelet aggregation associated with this polymorphism may be important in preventing acute rejection and its impact on chronic rejection.

Effects of nitric oxide donors sodium nitroprusside and 3-morpholino-sydnonimine on prolactin secretion in conscious rats.

In the present study, we have examined the possible involvement of the central nitric oxide (NO) pathway in the control of prolactin secretion in vivo. The effects of intracerebroventricular (i.c.v.) injections of L-arginine (L-Arg), a precursor of NO, N omega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO synthase (NOS), and of sodium nitroprusside (SNP) and 3-morpholino-sydnonimine (SIN-1), NO donors, on basal prolactin levels were studied in conscious male rats. Microinjections of L-Arg (100 and 500 mu g) or L-NAME (100 and 500 mu g) did not modify plasma prolactin levels, however i.c.v. injections of both SNP (1, 5, 10 and 20 mu g) and SIN-1 (1, 10 and 100 mu g) induced dose-dependent increases in these levels although SNP was much more potent than SIN-1. These results suggest a role of NO in the control of prolactin secretion.