Irradiation of Crotalus durissus terrificus crotoxin with 60Co gamma-rays induces its uptake by macrophages through scavenger receptors

Abstract

Purpose: To investigate the action of 2 kGy 60Co gamma-rays on crotoxin and its favoured uptake through scavenger receptor (ScvR) mouse peritoneal macrophages. Materials and methods: Native or irradiated crotoxin (iCTX) (50 mu g/ml) dosed with 2 kGy 60Co gamma-rays (dose-rate 540 Gy/h) were offered to mouse peritoneal macrophages; their uptake was evaluated by immunohistochemistry and quantitative in situ ELISA. Receptors recognizing irradiated crotoxin were evaluated with specific ScvR blockers (Probucol and dextran sulphate) or with non-specific blocking using foetal calf serum (FCS). Results: Immunohistochemical assays revealed more deeply staining intracytoplasmic vacuoles in macrophages incubated with iCTX. Using in situ ELISA with ScvR specific blockers, it was shown that the increased uptake of iCTX was blocked by Probucol or dextran sulphate, but not by FCS. On the other hand, the uptake of native crotoxin was decreased by FCS, but not affected by ScvR blockers. The morphology and viability of macrophages were preserved during the experiments. Conclusions: It is concluded that 60Co gamma-rays probably induced oxidative changes in crotoxin, driving this toxin towards ScvR mouse peritoneal macrophages. This suggests a different in vivo route of iCTX away from toxic neural sites by a preferential and rapid internalization and processing by macrophages, leading to the induction of a better immune response.