Serum samples from patients with meningococcal disease were examined for the presence of IL-6, TNF-alpha, and LPS. Median serum concentration of IL-6 was 1,000 times higher in patients with septic shock (189 ng/ml) than in patients with bacteriaemia, meningitis, or combined septic shock and meningitis. 11 of 21 patients with serum levels greater than 3.0 ng/ml died, whereas all 58 patients with serum levels at less than or equal to 3.0 ng/ml, survived. All four patients with serum IL-6 levels greater than 750 ng/ml, died. IL-1 was detected in serum from three patients who also had high serum levels of IL-6, TNF-alpha, and LPS, and rapidly fatal courses. IL-6 appeared to be released into serum later than TNF-alpha, and was detected in serum for up to 36 h. The half-life of IL-6 and TNF-alpha was calculated to be 103 +/- 27 min and 70 +/- 11 min, respectively. These data indicate that a complex pattern of cytokines exists in serum from patients with meningococcal septic shock, and that the release of IL-6 and IL-1, in addition to TNF-alpha, is associated with fatal outcome.