Neutrophils in the interface between innate and adaptive immunity in response to Haemophilus influenzae type a

Abstract

Haemophilus influenzae type a (Hia) is a bacterial human pathogen that has emerged as a significant cause of invasive disease in Canadian Indigenous populations. Protection against encapsulated bacteria such as Hia is mediated by the antigen-specific antibody response, in cooperation with innate immune mechanisms. Anti-capsular antibodies and complement opsonize bacteria for phagocytosis. Neutrophils are abundant innate immune cells primarily involved in bacterial clearance via opsonophagocytosis. Recent studies revealed they can modulate the adaptive immune response, but this function is poorly understood. Also, much is still unknown about the innate and adaptive immune responses to Hia and its polysaccharide capsule. As such, this study aimed to determine if Hia can activate the innate and adaptive immune responses through neutrophils and if these responses differ between encapsulated versus unencapsulated, or invasive versus non-invasive strains. [...]