Group B Streptococcus Induces a Robust IFN-γ Response by CD4+ T Cells in an In Vitro and In Vivo Model

Abstract EN

Group B Streptococcus (GBS) serotype III causes life-threatening infections.

Cytokines have emerged as important players for the control of disease, particularly IFN-γ.

Although potential sources of this cytokine have been proposed, no specific cell line has ever been described as a leading contributor.

In this study, CD4+ T cell activation profiles in response to GBS were evaluated through in vivo, ex vivo, and in vitro approaches.

Total splenocytes readily produce a type 1 proinflammatory response by releasing IFN-γ, TNF-α, and IL-6 and actively recruit T cells via chemokines like CXCL9, CXCL10, and CCL3.

Responding CD4+ T cells differentiate into Th1 cells producing large amounts of IFN-γ, TNF-α, and IL-2.

In vitro studies using dendritic cell and CD4+ T cell cocultures infected with wild-type GBS or a nonencapsulated mutant suggested that GBS capsular polysaccharide, one of the major bacterial virulence factors, differentially modulates surface expression of CD69 and IFN-γ production.

Overall, CD4+ T cells are important producers of IFN-γ and might thus influence the course of GBS infection through the expression balance of this cytokine.