Abstract

A Short Note on T Follicular Helper Cells.

Author(s): Katy Wilson

A single dose of the replication-competent, live-attenuated Yellow Fever Virus (YFV) 17D vaccine provides lifelong protection against YFV infection in humans. B cell responses to YFV 17D are less well understood than T cell responses in terms of magnitude, kinetics, and specificity. We focused on early immune events critical for the development of humoral immunity to YFV 17D vaccination in 24 study subjects in this clinical study. FluoroSpot analysis confirmed that plasmablasts were YFV-E protein specific. T follicular helper cells (Tfh) are a type of CD4+ T cell that was discovered in the human tonsil. They play an important role in protective immunity by assisting B cells in producing antibodies against foreign pathogens. Despite the existence of an effective vaccine, recent outbreaks of Yellow Fever (YF) in South America and Sub-Saharan Africa demonstrate that YF remains a serious global health problem. Numerous studies have examined and confirmed the development of protective immunity following YFV 17D vaccination by characterising YFV-specific T cell and Ab responses. B and T cell interactions are required for the effective generation of protective neutralising Abs and immunological memory. This interaction takes place primarily in secondary lymphoid organ germinal centres. The magnitude, kinetics, and specificity of the B cell response to YFV 17D have not been as extensively studied as T cell responses. Recent studies on early B cell responses to vaccination with YFV 17D indicate that there is an expansion of plasmablasts in peripheral blood.