Descriptive Study of the Evolution in Proportion of Regulatory B Lymphocytes in Patients Hospitalized in Intensive Care for Severe Sepsis

Inclusion Criteria: * Adult patients with severe sepsis or septic shock diagnosed less than 24 hours (defined as D0) and hospitalized in the medical resuscitation department of the Amiens-Picardie University Hospital. * The definitions of severe sepsis and septic shock are the result of the consensus of the Société de Réanimation de Langue Française dating from 2005: * Sepsis refers to a systemic inflammatory response syndrome (SIRS) in the presence of suspected or identified infection. Sepsis is said to be severe when lactate\> 4 mmol / L or arterial hypotension prior to filling or organ dysfunction is present (one is sufficient): hypoxemia with a PaO2 / FIO2 \<300 ratio, renal failure with Hepatic insufficiency with INR\> 4 or bilirubin\> 78 μmol / l, thrombocytopenia (platelets \<100 000 / mm3) and hepatic insufficiency\> 176 μmol / l, coagulation disorders with INR\> 1.5 Disorders of higher functions with a Glasgow Coma Score \<13. * Finally, septic shock is defined as a severe sepsis condition with persistent hypotension despite a well-conducted vascular filling (20-40 ml / kg isotonic saline). Exclusion Criteria: * Patient with active neoplasia, immune deficiency, autoimmune disease or autoimmune disease. * Patient under tutorship or curatorship * Taking an immunomodulatory or immunosuppressive treatment at the time of the study or the year prior to hospitalization for sepsis. * Antecedent or haematopoietic graft in progress. * Pregnancy in progress. * Known history of infection with human immunodeficiency virus (HIV) type 1 or 2 or with hepatitis B or C virus * Patient with agranulocytosis (defined as neutrophils \<0.5 G / L).