Abstracts (complete list) - Wissenschaft Online

Nicole Bethke, Matthias Böthe, Siegfried Kohler, Matthias Niedrig, Andreas Thiel
Bystander activation of recall antigen-specific CD4+ T-cells
during primary immunization with live attenuated yellow
fever virus
Immunization with the attenuated yellow fever virus 17D-204 confers protection in the
majority of vaccinees. However, the underlying mechanisms for the generation of
specific cellular immunity have remained unclear so far. To gain insight into vaccinationinduced
immunological processes we have analyzed absolute and relative frequencies of
various immunocyte subsets and assessed yellow fever vaccine-specific and bystander
activated CD4+ T-cells.
Human blood was obtained from 8 healthy volunteer donors before and at 8 time points
after vaccination with yellow fever virus 17D-204. Absolute and relative frequencies of
CD4, CD8, DC, NK and B-cell subsets were analyzed by multicolour flow cytometry.
Antigen-specific CD154+ CD4+ T-cell were analyzed for expression of IL-2, IFNγ, TNFα,
IL-4 and IL-10 after stimulation with yellow fever vaccine 17D-204, recall antigens
(CMVpp65, TT) and SEB.
Hitherto all vaccinees responded with significant generation of yellow fever vaccinespecific
CD154+ CD4+ T-cells with maximum responses for IL-2, IFNγ, TNFα and IL-4
between day 10-14. In 6 out of 8 donors increased frequencies of CMV and/or TTspecific
CD154+ CD4+ T-cells peaked shortly before or in parallel to the appearance of
yellow fever vaccine-specific T-cells.
Our data demonstrate that primary yellow fever immunization induces vaccine-specific
CD4+ T-cells but also mobilizes recall antigen-specific CD4+ T-cells with polyfunctional
features.