The incidence of infectious complications (nosocomial infections) of hospitalized patients in intensive care is major. It is linked both to the use of vulvar procedures necessary for the resuscitation measures (catheters, intubation, urinary probing ...), but also, in some patients, to a state of acquired immunodepression. This state of immune failure responsible for the persistence of the initial infectious, nosocomial infections and excess mortalityhas mainly been describedduring sepsis in humans. Indeed, it was found that a large proportion of patients surviving the first pro-inflammatory phase of sepsis died in the following days or weeks of infectious complications. However, these acquired immunodeficiency phenomena begin to be described after major surgery and acute non-infectious aggression. The various research projects of our team study the immunosuppressive mechanisms responsible for over-exposure of patients to nosocomial infections. Myeloid cells are particularly studied.