[Immunology in clinical practice. VIII. Role of cytokines in the pathogenesis of bacterial infections].

Cytokines are small proteins that can be produced by many different cell types involved in inflammation. The cytokine network consists of pro-inflammatory cytokines, facilitating inflammation, and anti-inflammatory cytokines, reducing inflammation at least in part by inhibiting the production of pro-inflammatory cytokines. The production of cytokines is enhanced during bacterial infections. The balance between pro- and anti-inflammatory cytokines critically determines the outcome of infection. Excessive systemic release of pro-inflammatory cytokines such as tumour necrosis factor alpha and interleukin 1 may contribute to organ failure in patients with fulminant sepsis. On the other hand, the local action of pro-inflammatory cytokines, at the site of a compartmentalized infection, is required for an adequate host antibacterial defence. Therefore, neutralization of pro-inflammatory cytokines may benefit some patients with bacterial sepsis but harm others.