Chenouard A, Chesneau M, Braza F, Dejoie T, Cinotti R, Roquilly A, Brouard S, Asehnoune K. Mol. Immunol. 2015; 68(2 Pt A): 350-356.
Affiliation
Intensive Care Unit, Anesthesia and Critical Care Department, Nantes University Hospital, Nantes, France; Thérapeutiques Cliniques et Expérimentales des Infections, EA 3826 Nantes, France. Electronic address: karim.asehnoune@chu-nantes.fr.
BACKGROUND: Brain injuries (BI) induce a state of systemic immunosuppression, leading to a high risk of pneumonia. In this pilot study, we investigated the status of B cell compartment in BI patients.
METHODS: A prospective observational study was performed in 2 intensive care units in a university hospital. Blood samples were collected in 14 patients at day 1 and day 7 after acute BI. The phenotype and the ability of B cells to secrete IL-10 were compared to 11 healthy volunteers (HV).
RESULTS: Among the circulating lymphocytes, the frequency of B cells was significantly higher in BI patients compared to HV (p<0.001). B cells from BI patients displayed an activated profil on day 7 after BI, reflected by a significantly higher proportion of CD27(+) memory (p=0.01) and CD27(+) IgD(-) switched memory B cells (p=0.02), as well as a significantly higher blood level of IgA (p=0.001) and IgM (p<0.001) as compared to day 1. The frequency of IL-10 secreting B cells (IL-10(+) B cells) on day 1 and day 7 was significantly lower in BI patients compared to HV (p<0.05). Interestingly, we observed that all BI patients with high frequency of IL-10(+) B cells on day 1 displayed an episode of pneumonia, and had a longer duration of mechanical ventilation and ICU stay compared to BI patients with low proportion of IL-10(+) B cells.
CONCLUSION: This study provides an extensive description of the phenotype and function of B cells in BI patients. Our results suggest that IL-10(+) B cells could play a major role in immunosuppression after BI.