ELEVATED NUMBER OF CIRCULATING PLASMABLASTS IN PATIENTS WITH ACUTE HANTAVIRUS PULMONARY SYNDROME CAUSED BY ANDES VIRUS INFECTION

GARCÍA M; MARTÍNEZ V; IGLESIAS A; LANDONI V; SASIAIN MC; SCHIERLOH P

Mar del Plata

Congreso; LXII Reunión Anual de la Sociedad Argentina de Inmunología; 2014

Sociedad Argentina de Inmunología (SAI)

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. In order to characterize the phenotype of those immunoblasts in HPS patients caused by the Andes virus (ANDV), anticoagulated blood samples were obtained from confirmed HPS patients (ANDV+ n=12), seronegative patients with acute respiratory symptoms (ARS n=12) and healthy subjects (HS n=21). Samples were inactivated and stabilized under biosecure conditions and processed for flow cytometry and confocal microscopy for quantitative (CountBright?) and qualitative analysis. 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 0,0012) and less frequent in ARS (p 0.02). PB level dropped in ANDV+ late samples (n=4), resembling the ones observed in HS. In addition, ANDV+ with low IgG anti-NP titer show higher PB levels than those with high titer (p 0.02), which could be related with the fact that IgG increases with the progress of the disease. Finally, flow-sorted ANDV+-derived PB analyzed by confocal microscopy exhibit intracellular Igs contents and bigger size than CD38low/neg B-lymphocytes (p 0,05). This phenotype resembles the immunoblast-like cell shape often described during cytology exam. As recently reported for other RNA viruses (i.e.Dengue and Influenza), our results show that ANDV+ present a massive and transient PB response, corresponding to what has previously been morphologically defined as immunoblasts. The antigen specificity of these cells remains to be addressed as well as their role during the course of the disease.