ICU With Sepsis Inclusion Criteria:
* Age ≥ 18
* Presumed diagnosis of sepsis, defined as "patients with life-threatening organ dysfunction caused by a dysregulated host response to infection"
* Patients in the ICU who meet 2 or more of the quick SOFA (qSOFA) definition along with organ dysfunction:
1. Respiration rate ≥ 22 breaths/min and/or mechanically ventilated
2. An alteration in mental status
3. Systolic blood pressure of less than 100 mm Hg and/or receiving inotropes to maintain blood pressure AND/OR
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1. An acute change in SOFA score ≥2 points, consequent to the infection (can assume SOFA score = 0 in patients with no pre-existing organ dysfunction)
ICU Without Sepsis Inclusion Criteria:
* Age ≥ 18
* Patients requiring care at a M Health Fairview ICU due to high acuity of illness and no other evidence of sepsis
Healthy Volunteer Inclusion Criteria
* Age greater or equal to 18
* ASA status 1, 2 or 3
* May include patients who are receiving dialysis in an outpatient setting
Exclusion Criteria (all groups):
* Active cancer with chemotherapy and/or radiation treatment within the past 6 weeks
* Medication usage that includes immunosuppressive drugs, biologic agents, cytokines, growth factor and interleukins
* Steroid medication usage of \> 300mg hydrocortisone per day (equivalent of \> 20mg prednisone). Patients with chronic steroid use will be excluded, however patients who have had stress dose steroids administered following admission will be included.
* Patients with a history of, or who currently have evidence of autoimmune disease, including but not limited to: myasthenia gravis, Guillain Barré syndrome, systemic lupus erythematosus, multiple sclerosis, scleroderma, ulcerative colitis, Crohn's disease, autoimmune hepatitis, Wegener's granulomatosis, HIV/AIDS, etc.
* Patients with active or a history of acute or chronic lymphocytic leukemia
* Known history of chronic hepatitis B (HBV) infection and not on treatment with HBV nucleoside analogues prior to the current hospitalization, or HBV DNA \> 100 IU/mL
* Known history of infection with hepatitis C (HCV) and currently undergoing treatment for HCV infection or has detectable HCV RNA
* Participation in another investigational interventional drug study within the past 4 weeks
* Current pregnancy
* Current incarceration
