Prevention of suppressed cell-mediated immunity in burned mice with histamine-2 receptor antagonist drugs

The effect of antioxidant therapy on cell-mediated immunity following burn injury in an animal model

Although antioxidant therapy has been introduced into early post burn protocols to prevent oxidative injury, it is still not known how they effect the cellular immunity which was already depressed due to thermal injury. To investigate the effect of antioxidant therapy on postburn immunosuppression following burn injury in a rat model, well known antioxidants: allopurinol (50 mg/kg/day), desferrioxamine (15 mg/kg/day), PEG-catalase (PEG-CAT) (1200 U/kg/day), N-acetylcysteine (NAS) (1 mg/kg/day) and vitamin-C (Vit-C) (0.5 mg/kg/day) were given for 7 days following thermal injury. The immunologic status of the rat was studied using two in vivo measures at seventh day following (30% TBSA) full-thickness burn injury. The contact hypersensitivity response (CHR) of rats, and their ability to induce a host versus graft reaction (HVGR) in the popliteal node were used to assess immune system as in vivo measures. The use of mentioned antioxidants resulted in significant improvement (between P < 0.05 and P < 0.001) of burn induced immunosuppression as reflected by CHR. The treatment with allopurinol and PEG-CAT (P < 0.01) significantly improved, while desferrioxamine, NAS and Vit-C improved, but not significantly, HVG reaction in burned rats. This study demonstrated that a large burn was profoundly immunosuppressive and early intervention of antioxidant therapy was able to significantly restore cell-mediated immunity as reflected by two in vivo assays.

Ranitidine for prevention of postoperative suppression of delayed hypersensitivity

Cell-mediated immunity was assessed by skin testing with seven delayed-type common antigens in 20 patients undergoing major abdominal surgery and in 20 nonoperative control subjects. The 20 surgical patients were randomized to perioperative ranitidine (50 mg every 6 hours for 72 hours) or no ranitidine. The 20 control subjects received either no ranitidine or ranitidine in the same dosage as the surgical patients. Skin tests were performed 2 days before and 1 day after operation with the same time schedule in the control subjects. Postoperatively, the diameter of the positive skin test area decreased in each of 10 patients without ranitidine (p less than 0.006) but increased in 9 and was unchanged in 1 of the ranitidine-treated patients (p less than 0.01). The skin test changes were similar during the two tests in ranitidine-treated surgical patients and the nonoperative control subjects. Ranitidine did not amplify the response in the nonoperated group. The potential role of histamine blockade in reversal of other aspects of postoperative immunosuppression and reduction in the risk of infection should be explored.