Virus Specific and Bystander-B cell Activation account for a Massive Plasmablast Response in Andes virus Infected Patients

GARCIA M.; IGLESIAS A; LANDONI V; BELLOMO C; BASSI SC; BRUNO A; CORDOBA MT; SASIAIN MC; MARTINEZ VP; KLINGSTRÖM J; SCHIERLOH LP

Fort Collins, Colorado

Conferencia; International Conference on HFRS, HPS and Hantaviruses; 2016

Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences

Objective: The presence of ?immunoblast-like? cells in patients with Hantavirus Pulmonary Syndrome (HPS) is a regular finding during routine clinical blood exam. Nonetheless their cellular linage has not been established nor their relevance in the course of the disease. Therefore, we aimed to characterize the phenotype of those immunoblasts in HPS patients infected with Andes virus (ANDV). Methods: Anticoagulated blood samples were obtained from confirmed HPS patients (ANDV+ n=18), seronegative patients with acute respiratory symptoms (ARS n=15) and healthy subjects (HS n=21). Samples were inactivated and stabilized and processed for flow cytometry and confocal microscopy. Additionally, the red blood cells from samples from ANDV+, ARS, HS, influenza vaccinated HS (v-HS, n=12) and tuberculosis patients (TB, n=10) were lysed and intracytoplasmatic antibodies (cyAb) from leucocytes were obtained by non-anionic detergent extraction. CyAb were tested by indirect ELISA against ANDV specific antigens (Ags)/epitopes (n=4) and unrelated Ags (n=8). Results: In ANDV+ acute samples, we observed high numbers of CD19+ CD27hi CD38hi CD20neg IgDneg CD138+/neg intracellular Igshi blasted (FSChiSSChi) lymphoid cells identified as circulating plasmablasts (PB), a B cell-derived population virtually absent on HS (p