title: Regulation of aged humoral immune defense against pneumococcal bacteria by IgM memory B cell.
abstract: Elderly persons have a high incidence of lethal infections by encapsulated bacteria. However, mechanisms involved in their poor defense and maintenance of immunological memory have been poorly understood. The present study characterized the population of B cells known as IgM memory B cell compartment and their response by pneumococcal vaccine in elderly people. CD27+ memory B cells, particularly IgD+IgM+CD27+ IgM memory B cells, had dramatically declined in the aged. Their Ig syntheses by B cells and the differentiation into plasma cells were diminished in vitro compared with those in adults. A rise of anti-pneumococcal IgM in sera of elderly persons was found with lower levels compared with those in adults after pneumococcal vaccination. Although diminished function itself of aged B cells surely exist, decline of the IgM memory B cell pool is expected to result in a poor humoral immunity against pneumococcal infection in elderly people.
authors.affiliation: Department of Infectious Immunology, Shinshu University, Graduate School of Medicine, Asahi, Matusmoto, Japan.
authors.forename: Yuhui
authors.initials: Y
authors.lastname: Shi
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamazaki
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Okubo
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Uehara
authors.forename: Kazuo
authors.initials: K
authors.lastname: Sugane
authors.forename: Kazunaga
authors.initials: K
authors.lastname: Agematsu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000276:immunology*; D000907:Antibodies, Bacterial / Q000097:blood*; D000917:Antibody Formation; D001402:B-Lymphocytes / Q000276:immunology*; D005260:Female; D006801:Humans; D007072:Immunoglobulin D / Q000032:analysis; D007075:Immunoglobulin M / Q000097:blood*; D007156:Immunologic Memory; D008297:Male; D008875:Middle Aged; D022242:Pneumococcal Vaccines / Q000276:immunology; D013296:Streptococcus pneumoniae / Q000276:immunology*; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000032:analysis
chemical_list: D000907:Antibodies, Bacterial; D007072:Immunoglobulin D; D007075:Immunoglobulin M; D022242:Pneumococcal Vaccines; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7