B Lymphocyte Populations in the Pulmonary Microenvironment of Patients Under Mechanical Ventilation With or Without VAP (Ventilator-Associated Pneumonia)

Pilot Study Describing B Lymphocyte Populations in the Pulmonary Microenvironment of Patients Under Mechanical Ventilation With or Without VAP (Ventilator-Associated Pneumonia)

Diagnosis of VAP relies on a set of non-specific clinical, biological, and imaging criteria.

Understanding host-pathogen interactions and the mechanisms of deregulations leading to infection of pulmonary tissue appears essential.

The aim is to qualitatively describe the B lymphocyte populations present in the pulmonary microenvironment of patients admitted to intensive care and requiring invasive mechanical ventilation

The study of the immune system and host-pathogen interactions is the subject of extensive research to improve the understanding of pathophysiology, leading to more precise diagnostic criteria, and considering preventive or curative treatments while limiting the use of anti-infective molecules. Understanding host-pathogen interactions and the mechanisms of deregulations leading to infection of pulmonary tissue seems essential. The study of T lymphocyte populations has already been the focus of numerous investigations. However, regarding the humoral immune response, B lymphocyte populations and their roles have so far been little explored in this context. Nevertheless, the presence of B lymphocytes in pulmonary tissue has been proven, particularly in infectious, postinfectious, or postvaccination contexts, but currently, there are no published studies regarding the B lymphocytes role in the pathophysiology of VAP (Ventilator-Associated Pneumonia).

Respiratory samples (endotracheal aspirates) will be collected from patients under mechanical ventilation on the day of intubation (D0), the day before extubation (Dext), and the day of VAP diagnosis (DVAP) for patients who will develop it. The samples will be stored and then analyzed by flow cytometry.

Inclusion Criteria:

• Adult patients (≥18 years old), admitted to intensive care under mechanical ventilation for an estimated duration of at least 5 days.

Exclusion Criteria:

• Patients admitted for an infectious pneumonia or presenting with acute respiratory distress syndrome (ARDS). Patients in aplasia (leukocytes < 0.5 gigal/L).