The expression of mHLA-DR, measured by flow cytometry, is today the reference marker to guide immunostimulatory therapies (IFN-γ) in the most severely immunocompromised patients. Nevertheless, pre-analytical constraints (storage of samples at +4°C before analysis) limit the wide use of mHLA-DR in clinical practice (problem of transporting samples to sites with a flow cytometer). Recent studies have shown that samples taken on Cyto-Chex Blood Collection Tubes (BCT) (containing a cell membrane stabilizer) were, for mHLA-DR, stable at room temperature during 72 hours after sampling. The main objective of this study is to compare the expression of mHLA-DR from samples taken simultaneously from standard tubes (EDTA) and new generation Cyto-Chex BCT tubes, to validate using Cyto Chex BCT tube in the clinical practice.

The investigators think that mHLA-DR quantification performed from Cyto-Chex BCT tubes is reliable and similar to quantification performed from EDTA tubes.

Inclusion Criteria:

• Adult patient hospitalized in intensive care unit
• Patient able to consent and having expressed his non-objection (in the case where the patient is aware) OR Patient whose trusted person has given his non-objection (in the case where the patient is not able to consent, example intubated patient)

Exclusion Criteria:

• Pregnant women
• Minors
• Persons deprived of their liberty by a judicial or administrative decision
• Persons subject to psychiatric care
• Adults subject to a legal protection measure (guardianship, protection of vulnerable adults)
• Patient who doesn't understand French language

This study will focus on patients hospitalized in the intensive care unit of the Edouard Herriot hospital in Lyon