Immunity Markers in Intensive Care Patients and Ventilator-associated Pneumonia

The goal of this observational study is to show the direct correlation between the occurrence of recurrence of VAP and postagressive immunoparalysis, monitored by HLA-DR rate below litterature-acknowledged threshold, in a well conducted antibiotherapy context, in patient admitted in the Intensive Care Unit. The main questions it aims to answer are: * evaluation of the association between death and persistence of immunoplegia using HLA-DR monitoring * search an association between immunoplegia depth and severity of the initial state of shock * search an association between immunoplegia depth and viral reactivation * compare association of immunoplegia duration and HLA-DR nadir and VAP occurrence Blood samples will be taken from participants to HLA-DR dosage, at the time of inclusion and once a week then.