Scientists know surprisingly little about how flu vaccines
actually work. Now, new research suggests that a population of T
cells appears in the blood after seasonal influenza vaccination
and may boost the body’s development of protective antibodies
against the flu. Following two small groups of children and
adults for three years, Salah-Eddine Bentebibel and colleagues
at Baylor Research Institute, along with teams from Baylor
University, The Research Institute at Nationwide Children’s
Hospital, and Mount Sinai School of Medicine, discovered a
special subgroup of T cells that appear in blood after flu
vaccination. These CD4+ T cells express three markers—CXCR5,
CXCR3, and ICOS—and are correlated with the development of
protective antibodies against flu. Up to 60% of these
ICOS+CXCR3+CXCR5+CD4+ T cells were specific for influenza
antigens and expressed interleukin-2 (IL-2), IL-10, IL-21, and
interferon-γ upon antigen stimulation. The authors found that
these T cells work by helping pre-existing memory B cells