B cells naturally induced during dengue virus infection release soluble CD27, the plasma level of which is associated with severe forms of pediatric dengue.

The CD27 and CD38 antigens are highly expressed on the plasmablast surface, and a massive plasmablast response has been described for dengue virus infection. Soluble CD27 and CD38 forms (sCD27 and sCD38, respectively) increase after immune activation. Here, we show increased sCD27 release in cultures of purified polyclonally stimulated B cells. T and B cells isolated from children with dengue spontaneously produced higher levels of sCD27 but not sCD38, compared with healthy children (P=0.03), and sCD27 levels positively correlated with plasmablast frequency in the cultures (rho=0.58, P=0.01). Children with dengue had higher plasma levels of sCD27 and sCD38 than healthy children, which decreased during convalescence. Plasma sCD27 was higher in severe than with mild dengue, but the opposite was observed for sCD38. These findings support a potential new role for B cells in dengue pathogenesis, and sCD27 and sCD38 are novel biomarkers associated with clinical outcome during dengue virus infection.