The effect of the immunomodulator RU 41,740 (biostim) on the specific and nonspecific immunosuppression induced by thermal injury or protein deprivation

N. V. Christou, I. Zakaluzny, J. C. Marshall and C. W. Nohr
Department of Surgery, Royal Victoria Hospital, Montreal, Quebec, Canada.

We studied the effect of RU 41,740 (biostim), a primary macrophage stimulator, in the following two immunosuppressive conditions in rats: (1) a 30% full-thickness burn that leads to significant decreases in cell-mediated (delayed-type hypersensitivity [DTH]), humoral (anti-tetanus toxoid antibody production), and nonspecific immunity (Staphylococcus aureus 502a skin abscess) and (2) protein malnutrition using a 2% protein diet for eight weeks. Biostim administered by gastric intubation at dosages of 10 and 50 mg/kg of body weight for five days following thermal trauma did not prevent the DTH suppression induced by the thermal injury, but resulted in a significant dose-related increase in the amount of anti-tetanus toxoid antibody produced. In the malnourished rats given biostim at dosages of 10 and 50 mg/kg of body weight for seven days, there was a significant dose-related increase in the DTH response in the presence of continued protein depletion in these animals, with a modest but significant reduction in the S aureus 502a skin abscess at three days. Antibody production was not affected with this model. Biostim partially overcomes the suppression in humoral immunity following thermal injury, but not cell-mediated or nonspecific immunity. On the other hand, biostim augments both the cell-mediated and nonspecific immune suppression induced by prolonged protein deprivation but does not affect humoral immunity.