Effect of influenza immunization on CYP3A4 activity in vivo.

Many reports of interactions between drugs metabolized by CYP3A4 and influenza vaccine have been made. The authors hypothesized that changes in CYP3A4 activity following influenza immunization would correlate with cytokine production or age. Twenty-four subjects had an erythromycin breath test (ERMBT) and blood draw for lymphocyte culture prior to and on day 7 following influenza immunization. Cytokine production by lymphocytes cultured with influenza antigen was measured by ELISA. Eight men and sixteen women ranging in age from 20 to 66 years (mean = 38.7 years; SE = 2.9) participated in the study. Interferon gamma (IFNgamma) production inversely correlated with change in ERMBT (correlation coefficient = -0.614; p < 0.02), although the overall change in ERMBT was not statistically significant (mean = -4%; p = 0.28). The IFNgamma production correlates with change in ERMBT. This correlation supports in vitro findings of decreased CYP3A4 expression and activity with IFNgamma exposure.