title: The effect of aging on the frequency, phenotype and cytokine production of human blood CD4 + CXCR5 + T follicular helper cells: comparison of aged and young subjects.
abstract: BACKGROUND
  T cell-dependent B-cell responses decline with age, indicating declined cognate helper activity of aged CD4 + T cells for B cells. However, the mechanisms remain unclear. T follicular helper (Tfh) cells, a novel T helper subset, play an essential role in helping B cells differentiation into long-lived plasma cells in germinal center (GC) or short-lived plasma cells. In the present study, we proposed that there might existe changes of proportion, phenotype or cytokine production of blood Tfh cells in healthy elderly individuals compared with healthy young individuals.
  
  
  RESULTS
  The results showed that frequencies of aged blood CXCR5 + CD4 + Tfh cells increased compared with young subjects. Both aged and young blood CXCR5 + CD4 + Tfh cells constitutively expressed CD45RO, CCR7 and CD28, and few of these cells expressed CD69 or HLA-DR, which indicated that they were resting memory cells. There was no significant difference of IL-21 frequency production by aged blood CXCR5 + CD4 + Tfh determined by FACS compared with young individuals, however, aged PBMCs produced significantly higher levels of IL-21 evaluated by ELISA. Furthermore, there were no significant differences of percentages of IFN-γ, IL-4, IL-17 or IL-22 production by aged Tfh cells compared with their counterparts of young individuals respectively. However, frequencies of IL-17+ cells within aged CD4 + CXCR5-T cells were markedly lower than in the young individuals. Furthermore we observed different frequencies of IFN-γ, IL-17, IL-4 or IL-22 production by Tfh or by CD4 + CXCR5- cells in aged and young subjects respectively.
  
  
  CONCLUSIONS
  Our data demonstrated that the frequencies of blood memory CXCR5 + CD4 + Tfh cells increased in the elderly population. There were similar frequencies of Th characterized cytokine production such as IL-21, IFN-γ, IL-4, IL-17 or IL-22 in aged and young Tfh cells. However, aged PBMCs produced a significantly higher amount of IL-21 compare to young subjects.
authors.affiliation: Department of Pathology and Laboratory Medicine, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, China.
authors.forename: Maohua
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Department of Pathogenic Biology and Immunology, Guangzhou Hoffmann Institute of Immunology, School of Basic Sciences, Guangzhou Medical University, Guangzhou 510182, China.
authors.forename: Ruqiong
authors.initials: R
authors.lastname: Zou
authors.affiliation: Department of Pathology and Laboratory Medicine, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, China.
authors.forename: Huiquan
authors.initials: H
authors.lastname: Gan
authors.affiliation: Department of Pathogenic Biology and Immunology, Guangzhou Hoffmann Institute of Immunology, School of Basic Sciences, Guangzhou Medical University, Guangzhou 510182, China.
authors.forename: Zhimei
authors.initials: Z
authors.lastname: Liang
authors.affiliation: Department of Pathogenic Biology and Immunology, Guangzhou Hoffmann Institute of Immunology, School of Basic Sciences, Guangzhou Medical University, Guangzhou 510182, China.
authors.forename: Fujun
authors.initials: F
authors.lastname: Li
authors.affiliation: Department of Pathology and Laboratory Medicine, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Lin
authors.affiliation: Department of Pathology and Laboratory Medicine, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, China.
authors.forename: Yanfei
authors.initials: Y
authors.lastname: Luo
authors.affiliation: Department of Pathology and Laboratory Medicine, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Cai
authors.affiliation: Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou 510150, China.
authors.forename: Fang
authors.initials: F
authors.lastname: He
authors.affiliation: Department of Pathogenic Biology and Immunology, Guangzhou Hoffmann Institute of Immunology, School of Basic Sciences, Guangzhou Medical University, Guangzhou 510182, China.
authors.forename: Erxia
authors.initials: E
authors.lastname: Shen
keywords: Aging; IL-21; Tfh cells