CD27 and COVID-19: Similarly, Kaneko et al. showed that patients with COVID-19 had lowered peripheral blood relative and absolute numbers of naïve IgD+CD27− cells, transitional IgD+CD27−CD10+CD45RB− and follicular CXCR5+ (IgD+CD27−CD10−CD73+) B cells compared with control subjects or convalescent patients [34].