Peritransplant streptavidin recipient treatment prolongs rat cardiac allograft survival.

BACKGROUND: Because streptavidin shows high localization in inflamed tissues, it might also interfere with the proliferation of cells involved in allograft rejection. METHODS AND RESULTS: Treatment of naïve ACI recipients with 20 mg/kg streptavidin i.p. alone significantly prolonged Lewis cardiac allografts from a mean survival time of 9.8+/-0.7 days in controls to 19.8+/-6.5 days, with one recipient accepting the graft permanently (>250 days). Peritransplant streptavidin treatment combined with 0.5 ml of antilymphocyte serum (ALS) transient immunosuppression led to permanent graft survival (>250 days) in 6 of 10 recipients. Second-set skin grafts performed 60 days after the primary cardiac allograft were prolonged to 45 days, whereas the third party Wistar-Furth (WF) skin grafts were rejected in 15 days without the rejection of the primary Lewis cardiac allografts. Pathology of transplanted cardiac allografts at 100 days showed no mononuclear cell infiltration or chronic allograft vasculopathy. Streptavidin given for 5 days at 20 mg/kg caused a moderate initial weight loss but had no effect on hematologic, biochemical, and histologic parameters in the treated recipients. CONCLUSION: This study demonstrates that peritransplant recipient treatment with streptavidin combined with peritransplant ALS induces prolonged cardiac and second-set skin allograft survival. We conclude that recipient peritransplant streptavidin treatment may provide a new strategy for the induction of transplant tolerance.

In nonhuman primates intracarotid adenosine, but not sodium nitroprusside, increases cerebral blood flow.

UNLABELLED: Intracarotid infusion of short-acting vasodilators, such as adenosine and nitroprusside, in doses that lack significant systemic side effects, may permit controlled manipulation of cerebrovascular resistance. In this experiment we assessed changes in cerebral blood flow (CBF) after intracarotid infusion of nitroprusside and adenosine. The study was conducted on six adult baboons under isoflurane anesthesia and controlled ventilation. Intracarotid drug infusion protocol avoided hypotension during nitroprusside infusion and tested for autoregulatory vasoconstriction. CBF (intraarterial (133)Xe technique) was measured four times during infusions of 1) intracarotid saline, 2) IV phenylephrine (0.2 microg x kg(-1) x min(-1)) aimed to increase mean arterial pressure by 10-15 mm Hg, 3) IV phenylephrine and intracarotid nitroprusside (0.5 microg x kg(-1) x min(-1)), and 4) intracarotid adenosine (1 mg/min). IV phenylephrine increased mean arterial pressure (69 +/- 8 to 91 +/- 9 mm Hg, P < 0.0001, n = 6), and concurrent infusion of intracarotid nitroprusside reversed this effect. However, compared with baseline, CBF did not change with IV phenylephrine or with concurrent infusion of IV phenylephrine and intracarotid nitroprusside. Intracarotid adenosine profoundly increased CBF (from 29 +/- 8 to 75 +/- 32 mL x 100 g(-1) x min(-1); P < 0.0001). In nonhuman primates, intracarotid adenosine increases CBF in doses that lack significant systemic side effects, whereas intracarotid nitroprusside has no effect. Intracarotid adenosine may be useful for manipulating cerebrovascular resistance and augmenting CBF during cerebral ischemia. IMPLICATIONS: Intraarterial (133)Xe cerebral blood flow (CBF) measurements suggest that intracarotid adenosine, in a dose that lacks significant systemic side effects, profoundly increases CBF, whereas nitroprusside has no effect.(5-12)