Complement activation in septic shock patients.

To evaluate the status of the complement system and to determine the effects of corticosteroids on complement component levels in septic shock, C3, C4, and Factor B were measured in 42 patients with severe late septic shock. Serum levels of C4 and Factor B correlated with C3 levels (r = 0.48 and 0.64, respectively; p less than .01) in patients in shock for more than 4 h, but only Factor B correlated with C3 (r = 0.85; p less than .01) in patients in shock for 4 h or less. C3 and Factor B levels were significantly (p less than .05) lower in patients who died (12,174 +/- 1,524 CH50 U/ml and 14 +/- 1 mg/dl, respectively) than in patients who survived (18,418 +/- 2,833 CH50 U/ml and 21 +/- 2 mg/dl, respectively). Corticosteroids did not alter complement component levels. The alternative pathway appears to be activated early in septic shock, whereas the classical pathway is activated later. C3 and Factor B levels may predict survival of patients in septic shock. In this study, corticosteroids did not change the complement component levels of patients in late severe septic shock.