Immunoparalysis is a relatively frequent finding in critically ill patients treated in the i ntensive care unit. It is characterized by reduced monocyte HLA-DR expression below 30% and decreased production of tumor necrosis factor-a after stimulation with lipopolysaccharid ex vivo lower than 300 pg/ml. For the function of the immune system it means inadequate antigen presentation with subsequent defect in the nonspecific and specific immune response. It means also inadequate activity of the proinflammatory reactions which provide homeostasis. In this situation there is a prevalence of the antiinflammatory processes associated with adverse clinical prognosis. For the differentiation between infectious and noninfectious inflammation we use the level of procalcitonin and granulocyte CD64 expression. Immunoparalysis does not necessarily imply that infection is present, it can be also caused by the cytokines. The diagnosis of immunoparalysis helps us distinguish patients who are on the opposite sides of the function of the immune system – the patients with high production of the proinflammatory cytokines and the patients with a prevalence of the antiinflammatory response. This is starting point for immunomodulatory therapy in these patients.

        Key words: immunoparalysis – HLA-DR/CR14 – production of tumor necrosis factor – procalcitonin – immunomodulation