title: In vitro assessment of chemotaxis by peripheral blood neutrophils from adult and senescent C57BL/6 mice: correlation with in vivo responses to pulmonary infection with type 3 Streptococcus pneumoniae.
abstract: To assess the effects of advanced age on the ability of circulating neutrophils to respond to biologically relevant chemoattractants, cells were isolated from the peripheral blood of pathogen and disease-free C57BL/6 mice and evaluated in a microchemotaxis chamber. The responses of granulocytes obtained from senescent mice (26-28 months) to the chemotactic peptide, FMLP, and to leukotriene B4 were similar to those found with cells from the younger animals (8-10 months). In contrast, the migration of neutrophils in response to sonicated type 3 Streptococcus pneumoniae was significantly greater with cells from the older animals. Similarly, the chemotactic response of neutrophils to zymosan-activated serum was greater with cells and serum from the senescent animals; however, the enhanced chemotaxis exhibited by granulocytes from the aged mice was a consequence of serum factors. Following the deposition of viable type 3 S. pneumoniae into the lower respiratory tract, the neutrophil influx at 24 h after challenge was significantly greater in the senescent mice; however, age-related differences in survival rates and LD50 were not detected. Thus, in the C57BL/6 mouse, senescence is not associated with deficiencies in the response of neutrophils in vitro to chemoattractants that contribute to lung host defense against the pneumococcus; further, in this murine strain, advanced age does not result in an attenuation of the pulmonary inflammatory reaction to infection with type 3 S. pneumoniae.
authors.affiliation: Department of Medicine, Boston University Medical Center, Mass.
authors.forename: A L
authors.initials: AL
authors.lastname: Esposito
authors.forename: W J
authors.initials: WJ
authors.lastname: Poirier
authors.forename: C A
authors.initials: CA
authors.lastname: Clark
mesh_terms: D000375:Aging / Q000276:immunology*; D000818:Animals; D002633:Chemotaxis / Q000502:physiology*; D004195:Disease Models, Animal; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D009504:Neutrophils / Q000032:analysis / Q000276:immunology*; D011024:Pneumonia, Viral / Q000276:immunology*; D013290:Streptococcal Infections / Q000276:immunology*; D013296:Streptococcus pneumoniae