Scientists probe why sepsis weakens the immune system

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. ICU patients with severe infections (Sepsis-3 definitions): clinically or microbiologically documented infection and organ dysfunction graded as follows: * Sepsis: increase in the Sequential Organ Failure Assessment (SOFA) score of 2 points or more. * Septic shock: vasopressor requirement to maintain a mean arterial pressure ≥ 65mmHg and serum lactate level \> 2 mmol/L in the absence of hypovolemia 2. ICU patients with non-septic acute circulatory failure: * Cardiogenic shock: left ventricle systolic dysfunction (echocardiographic left ventricular ejection fraction \< 45%) and the need of vasopressor (norepinephrine at any dose and inotropic support (dobutamine ≥ 5 µg/kg/min or epinephrine at any dose) in the absence of patent infection. * Severe hemorrhage: hypotension with acute blood loss requiring transfusion of at least four packed red cells within 24h and vasopressor support by norepinephrine or epinephrine at any dose. 3. Healthy controls: * Blood donors * Patients undergoing elective cataract surgery Exclusion Criteria: 1. All ICU patients * hematological malignancy (or significant history of bone marrow disease), * HIV infection at any stage, * any immunosuppressive drugs including corticosteroids ≥ 0.5 mg/kg equivalent prednisone per day for more 7 days, * anticancer chemotherapy or chemotherapy received during the last three months before inclusion * bone marrow or solid organ transplantation, * leucopenia (\<1000/mm3) excepted if due to sepsis, * pregnancy * do-not-resuscitate order at ICU admission * patients under legal protection regimen. 2. Healthy controls * history of inflammatory disease * hematological malignancy (or significant history of bone marrow disease), * HIV infection at any stage, * any immunosuppressive drugs including corticosteroids ≥ 0.5 mg/kg equivalent prednisone per day for more 7 days, * anticancer chemotherapy or immunotherapy received during the last three months before inclusion * bone marrow or solid organ transplantation, * pregnancy * infectious symptoms within the previous month * subjects under legal protection regimen