title: Th17/Th1 biased immunity to the pneumococcal proteins PcsB, StkP and PsaA in adults of different age.
abstract: Streptococcus pneumoniae is a major human pathogen, causing high morbidity and mortality in children, and also in the elderly, who are particularly susceptible to S. pneumoniae infections due to the dysregulated function of the aged immune system. As the current generation of polysaccharide vaccines do not provide sufficient protection for elderly, new vaccination strategies are urgently needed. To learn whether pneumococcal proteins are able to induce adaptive immune responses in adults in different age groups, we determined serum IgG antibody titers and T cell immunity (IFN-γ, IL-17A and IL-5 production) to three pneumococcal antigens, PcsB, StkP and PsaA, that are components of an investigational protein-based pneumococcal vaccine, IC47. Therefore, sera and PBMCs of 108 healthy adults in three different age groups (young, middle-aged and elderly) were analyzed by ELISA and ELISpot, respectively. We found naturally acquired antibodies to all three proteins in all age groups against all three antigens. However, elderly individuals had significantly lower IgG levels to PcsB and PsaA compared to those of younger donors. There was no significant age-related difference in the overall rate of T cell immunity for the three pneumococcal proteins. We found that the Th17 response was dominant in all age groups and was frequently combined with a Th1 or Th2 response in young and middle-aged subjects. However, in elderly persons there was a lower percentage of PBMC samples producing more than one cytokine upon antigenic stimulation. The narrow cytokine secretion pattern was the most striking difference between elderly and younger adult age groups. Our results demonstrate that in the majority of adults there is a naturally acquired humoral and cellular immune response to the three pneumococcal proteins tested. The dominance of the Th17 response is especially interesting in the light of new insights regarding the role of Th17 cells in mucosal protection against this pathogen.
authors.affiliation: Immunology Division, Institute for Biomedical Aging Research, Austrian Academy of Sciences, Rennweg 10, 6020 Innsbruck, Austria.
authors.forename: Petra
authors.initials: P
authors.lastname: Schmid
authors.forename: Sanja
authors.initials: S
authors.lastname: Selak
authors.forename: Michael
authors.initials: M
authors.lastname: Keller
authors.forename: Barbara
authors.initials: B
authors.lastname: Luhan
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Magyarics
authors.forename: Stefan
authors.initials: S
authors.lastname: Seidel
authors.forename: Petra
authors.initials: P
authors.lastname: Schlick
authors.forename: Christoph
authors.initials: C
authors.lastname: Reinisch
authors.forename: Karen
authors.initials: K
authors.lastname: Lingnau
authors.forename: Eszter
authors.initials: E
authors.lastname: Nagy
authors.forename: Beatrix
authors.initials: B
authors.lastname: Grubeck-Loebenstein
mesh_terms: D018829:Adhesins, Bacterial / Q000276:immunology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000276:immunology*; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology; D006801:Humans; D008074:Lipoproteins / Q000276:immunology*; D008875:Middle Aged; D011008:Pneumococcal Infections / Q000276:immunology / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000008:administration & dosage / Q000276:immunology*; D013296:Streptococcus pneumoniae / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology*; D058504:Th17 Cells / Q000276:immunology*; D014611:Vaccination; D055815:Young Adult
chemical_list: D018829:Adhesins, Bacterial; D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D008074:Lipoproteins; D022242:Pneumococcal Vaccines; C085000:PsaA protein, Streptococcus