Serum complement levels in canine endotoxin shock: relation to survival and to corticosteroid therapy.

Recent studies suggest prominent roles of the complement system in endotoxin shock and steroid-complement interactions in its treatment. To assess further the potential importance of the complement system in this condition, we measured serum total complement levels in dogs after an IV bolus of 1.5 mg/kg DIFCO E coli endotoxin. Dogs were assigned to control (C), dextran40 (LMD), or LMD + steroid groups. Corticosteroids, given IV 15 min after endotoxin, were 1) methylprednisolone sodium succinate (MPSS), 30 mg/kg; 2) dexamethasone sodium phosphate (DSP), 6 mg/kg; 3) hydrocortisone sodium succinate (HSS), 150 mg/kg; or 4) hydrocortisone sodium phosphate (HSP), 150 mg/kg. LMD was infused to maintain BP greater than 60% of preshock levels during the 4 h of monitoring. Survival rates at 48 h were C--7/24 (29%); LMD--3/12 (25%), MPSS--11/19 (59%) (P less than 0.1); DSP--9/14 (64%) (P less than 0.05); HSS--3/10 (30%) HSP--5/10 (50%). Within 15 min of endotoxin administration, serum complement titers fell at least 48% in all groups. Complement levels returned to the preshock range in only the LMD group. Mean complement levels of all survivors and nonsurvivors were nearly identical throughout the acute experiment. The results indicate that survival in canine endotoxin shock, with or without corticosteroid therapy, is not related to normalization of serum total complement titers during the first few hours after endotoxin injection.