Granzyme B: a marker of risk for influenza in institutionalized older adults.

Risk for influenza increases with age while cellular immune responses decline. This was a prospective study to determine the relationship between cytokine and granzyme B levels in peripheral blood mononuclear cells stimulated with live influenza virus, and subsequent influenza illness. Granzyme B levels were lower in the group who later developed symptomatic laboratory-confirmed influenza (n=10) compared to the group who did not (n=90) (ANOVA, P=0.024). In contrast, none of the cytokine levels were related to the development of influenza. Thus, granzyme B is a potential marker of influenza risk in older adults.