Circulating CXCR5+CD4+ T Follicular-Like Helper Cell and Memory B Cell Responses to Human Papillomavirus Vaccines

Through the interaction of T follicular helper (Tfh) cells and B cells, efficacious vaccines can generate high-affinity, pathogen-neutralizing antibodies, and memory B cells. Using CXCR5, CXCR3, CCR6, CCR7, PD1, and ICOS as markers, Tfh-like cells can be identified in the circulation and be classified into three functionally distinct subsets that are PD1(+)ICOS(+), PD1(+)ICOS(-), or PD1(-)ICOS(-). We used these markers to identify different subsets of CXCR5(+)CD4(+) Tfh-like cells in response to highly immunogenic and efficacious vaccines for human papillomaviruses (HPV): Cervarix and Gardasil. In this small study, we used PBMC samples from 11 Gardasil recipients, and 8 Cervarix recipients from the Vaccine Research Center 902 Study to examine the induction of circulating Tfh-like cells and IgD-CD38(Hi)CD27(+) memory B cells by flow cytometry. PD1(+)ICOS(+) CXCR3(+)CCR6(-)CXCR5(+)CD4(+) (Tfh1-like) cells were induced and peaked on Day (D) 7 post-first vaccination, but not asmuch on D7 post-third vaccination. We also observed a trend toward increase in PD1(+)ICOS(+) CXCR3(-)CCR6(-)CXCR5(+)CD4(+) (Tfh2-like) cells for both vaccines, and PD1(+)ICOS(+) CXCR3(-)CCR6(+)CXCR5(+)CD4(+) (Tfh17-like) subset was induced by Cervarix post-first vaccination. There were alsominimal changes in the other cellular subsets. In addition, Cervarix recipients had more memory B cells post-first vaccination than did Gardasil recipients at D14 and D30. We found frequencies ofmemory B cells at D30 correlated with anti-HPV16 and 18 antibody titers from D30, and the induction levels of memory B cells at D30 and PD1(+)ICOS(+)Tfh1-like cells at D7 post-first vaccination correlated for Cervarix. Our study showed that induction of circulating CXCR5(+)CD4(+) Tfh-like subsets can be detected following immunization with HPV vaccines, and potentially be useful as a marker of immunogenicity of vaccines. However, further investigations should be extended to different cohorts with larger sample size to better understand the functions of these T cells, as well as their relationship with B cells and antibodies.