Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.04.236521v1?rss=1 Authors: Adamo, S., Chevrier, S., Cervia, C., Zurbuchen, Y., Räber, M. E., Yang, L., Sivapatham, S., Jacobs, A., Bächli, E., Rudiger, A., Stüssi-Helbling, M., Huber, L. C., Schaer, D., Bodenmiller, B., Boyman, O., Nilsson, J. Abstract: Coronavirus disease 2019 (COVID-19), caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has a broad clinical presentation ranging from asymptomatic infection to fatal disease. Different features associated with the immune response to SARS-CoV-2, such as hyperinflammation and reduction of peripheral CD8+ T cell counts are strongly associated with severe disease. Here, we confirm the reduction in peripheral CD8+ T cells both in relative and absolute terms and identify T cell apoptosis and migration into inflamed tissues as possible mechanisms driving peripheral T cell lymphopenia. Furthermore, we find evidence of elevated serum interleukin-7, thus indicating systemic T cell paucity and signs of increased T cell proliferation in patients with severe lymphopenia. Following T cell lymphopenia in our pseudo-longitudinal time course, we observed expansion and recovery of poly-specific antiviral T cells, thus arguing for lymphopenia-induced T cell proliferation. In summary, this study suggests that extensive T cell loss and subsequent T cell proliferation are characteristic of severe COVID-19. Copy rights belong to original authors. Visit the link for more info