Cytokine and superoxide production in clinical stroke

Cytokines appear to play an important role in a variety of central nervous system (CNS) diseases and may be involved in ischemia. Activated leukocytes are a major source of cytokines and other inflammatory mediators that may directly injure ischemic CNS tissue. To investigate the importance of these substances in clinical stroke, we compared spontaneous secretion of IL-lβ, IL-6, IL-8, and superoxide production from neutrophils (PMN) and mononuclear cells (MNC) isolated from either acute stroke patients (n = 10) or matched controls (n = 10). Cytokine production from 5 × 10⁶ cells incubated for 24 h was determined by ELISA. MNC from acute stroke patients secreted significantly less IL-1β, IL-6, and IL-8 than MNC from control patients. No significant cytokine production was detected from PMN. Superoxide production from 1.25 × 10⁵ cells was determined over 1 h measuring cytochrome C reduction. There was a trend toward higher superoxide production in PMN from acute stroke patients, whereas the superoxide production in MNC from acute stroke patients was significantly higher than that of control MNC. This difference persisted even when various agonists were added preincubation. This study suggests that MNC spontaneous cytokine secretion is reduced in acute stroke patients, whereas superoxide production is increased. This decreased cytokine production may be secondary to the effects of a cytokine inhibitory factor.