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Healthy Elderly People Lack Neutrophil‐Mediated Functional Activity to Type V Group B Streptococcus
Author(s) -
Amaya Rene A.,
Baker Carol J.,
Keitel Wendy A.,
Edwards Morven S.
Publication year - 2004
Publication title -
journal of the american geriatrics society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.992
H-Index - 232
eISSN - 1532-5415
pISSN - 0002-8614
DOI - 10.1111/j.1532-5415.2004.52009.x
Subject(s) - medicine , antibody , phagocytosis , immunology , streptococcus pneumoniae , streptococcus , immunoglobulin g , ingestion , group b , microbiology and biotechnology , biology , antibiotics , genetics , bacteria
Objectives: To determine the function of capsular polysaccharide (CPS)‐specific immunoglobulin‐G (IgG) and neutrophils from older adults in increasing ingestion and killing of type V group B Streptococcus (GBS). Design: Cross‐sectional study. Setting: Outpatient clinic at Baylor College of Medicine. Participants: The subjects were 40 healthy, community‐dwelling adults aged 65 and older from Houston, Texas. Measurements: The serum level of type V GBS CPS‐specific IgG was measured using an enzyme‐linked immunosorbent assay. Functional activity was evaluated using an opsonophagocytosis assay. Results: Sera from four subjects promoted efficient neutrophil‐mediated phagocytosis and killing of type V GBS (mean log 10 reduction±standard deviation in colony‐forming units (cfu)=1.51±0.39). Each had serum CPS‐specific IgG concentrations exceeding 1 μg/mL. Sera from 36 subjects did not promote neutrophil‐mediated functional activity (mean log 10 reduction in cfu=−0.09±0.06; P =.025). Only one of these 36 had a CPS‐specific IgG concentration exceeding 1 μg/mL. When pooled sera from young adults given type V GBS conjugate vaccine was added at CPS‐specific IgG concentrations of 4 μg/mL or 0.4 μg/mL, sera from all subjects promoted neutrophil‐mediated killing of type V GBS. No impairment was evident in the neutrophil function of elderly subjects when it was compared with that of young adults. Conclusion: CPS‐specific IgG and neutrophils from healthy older adults function to ingest and kill type V GBS, but these antibodies are not present in sufficient amounts in most individuals. Further studies should determine whether a type V GBS vaccine induces functionally active antibodies in older people.