title: Impaired function of antibodies to pneumococcal surface protein A but not to capsular polysaccharide in Mexican American adults with type 2 diabetes mellitus.
abstract: The goal of the study was to determine baseline protective titers of antibodies to Streptococcus pneumoniae surface protein A (PspA) and capsular polysaccharide in individuals with and individuals without type 2 diabetes mellitus. A total of 561 individuals (131 individuals with diabetes and 491 without) were screened for antibodies to PspA using a standard enzyme-linked immunosorbent assay (ELISA). A subset of participants with antibodies to PspA were retested using a WHO ELISA to determine titers of antibodies to capsular polysaccharide (CPS) (serotypes 4, 6B, 9V, 14, 18C, 19A, 19F, and 23F). Functional activity of antibodies was measured by assessing their ability to enhance complement (C3) deposition on pneumococci and promote killing of opsonized pneumococci. Titers of antibodies to protein antigens (PspA) were significantly lower in individuals with diabetes than controls without diabetes (P = 0.01), and antibodies showed a significantly reduced complement deposition ability (P = 0.02). Both antibody titers and complement deposition were negatively associated with hyperglycemia. Conversely, titers of antibodies to capsular polysaccharides were either comparable between the two groups or were significantly higher in individuals with diabetes, as was observed for CPS 14 (P = 0.05). The plasma specimens from individuals with diabetes also demonstrated a higher opsonophagocytic index against CPS serotype 14. Although we demonstrate comparable protective titers of antibodies to CPS in individuals with and individuals without diabetes, those with diabetes had lower PspA titers and poor opsonic activity strongly associated with hyperglycemia. These results suggest a link between diabetes and impairment of antibody response.
authors: Division of Epidemiology, Human Genetics, and Environmental Health, University of Texas Health Science Center, School of Public Health, Brownsville Regional Campus, Brownsville, TX, USA.
authors: Christine E
authors: CE
authors: Mathews
authors: Eric L
authors: EL
authors: Brown
authors: Perla J
authors: PJ
authors: Martinez
authors: Upasana
authors: U
authors: Bagaria
authors: Moon H
authors: MH
authors: Nahm
authors: Robert L
authors: RL
authors: Burton
authors: Susan P
authors: SP
authors: Fisher-Hoch
authors: Joseph B
authors: JB
authors: McCormick
authors: Shaper
authors: S
authors: Mirza
mesh_terms: D000328:Adult; D000907:Antibodies, Bacterial / Q000097:blood*; D001426:Bacterial Proteins / Q000276:immunology*; D001770:Blood Bactericidal Activity; D003165:Complement System Proteins / Q000276:immunology; D003924:Diabetes Mellitus, Type 2 / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D017058:Mexican Americans; D008875:Middle Aged; D009895:Opsonin Proteins / Q000276:immunology; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D013296:Streptococcus pneumoniae / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D009895:Opsonin Proteins; D011135:Polysaccharides, Bacterial; C051592:pneumococcal surface protein A; D003165:Complement System Proteins