The course of prolonged sepsis is characterized by an initial activati
on of the immune system followed by the transition into a state of imm
unosuppression. Accordingly, a series of immunosuppressive substances
can be detected in the serum of septic patients. On the cellular level
many important functions of the unspecific as well as the specific de
fense systems of the organism are inhibited. As a consequence, immunos
uppression may be contributing to the fact, that patients suffering fr
om prolonged sepsis hardly recover with a high risk to end in multiple
organ dysfunction. However, increasing efforts to investigate this pr
oblem may result in therapeutic approaches which may help to improve t
he bad prognosis of sepsis.