Group B streptococci elicit leukotriene B4 and interleukin-8 from human monocytes: neonates exhibit a diminished response.

Neonatal monocytes have diminished function compared with adult cells. The ability to recruit neutrophils through elaboration of chemoattractants has not been evaluated in humans. The pattern of chemoattractant release induced by group B streptococci (GBS) also is unknown. Adult and cord blood monocytes were stimulated with GBS. Supernatants were used as the attractant in blind well chambers; migration to neonatal supernatants was diminished. Interleukin-8 (IL-8) and leukotriene B4 (LTB4) were released in greater quantities by adult monocytes in response to either GBS or lipopolysaccharide. Opsonization of GBS was not required for IL-8 release. Adult monocytes released more LTB4 when stimulated with unopsonized GBS than with opsonized GBS; the neonate's LTB4 production did not increase. IL-8 and LTB4 accounted for the majority of chemoattractant activity released in response to GBS. Decreased production of LTB4 and IL-8 may contribute to the neonate's poor host response to GBS.