Methods:The study was conducted during the 2007-2008 influenza season. We enrolled 69 community-dwelling individuals over 75-year old receiving standard (A/Solomon Islands/3/2006 (H1N1), A/Wisconsin/67/2005 (H3N2), and B/Malaysia/2506/2004) influenza vaccination. Pre and post-vaccination (in 4 weeks) TWEAK and antibody titers against each antigen were measured. The bivariate associations between TWEAK and potential demographic and medical history covariates were examined. We specified a regression model of post-vaccine TWEAK with adjustment for pre-vaccine TWEAK, and the influence of age, gender, hypertension, and frailty status.
Results:TWEAK level (mean= 690.6, SD= 330.0) significantly decreased after vaccination (mean= 591.7, SD= 290.1) (p= 0.003). Pre and post-vaccination mean CD163 levels were statistically equivalent (p= 0.71). Post-vaccination TWEAK was significantly lower in females (p= 0.01). There were no significant differences in post-vaccination TWEAK according to age, race, frailty status, mini mental status, marital status or history of heart failure, diabetes, heart attack, stroke, angina, or cancer. A time by frailty status interaction term was marginally significant (p= 0.091); decrease in TWEAK was greatest among frail people. A 2-fold antibody titer against H1 antigen was associated with significantly lower TWEAK (p= 0.031) level after vaccination. The effect of H1 antibody titer was not significant after adjustment for pre-vaccine TWEAK level. Mean TWEAK in hypertensive participants was significantly lower compared to those without hypertension (p= 0.04).
Conclusion: Influenza vaccine could have immune modulatory effect beyond influenza prevention. This effect could potentially be associated with immune response to some vaccine antigens. Future studies investigating this potential beneficial effect are warranted.
M. Keshtkarjahromi, None
S. Almed, None
H. Li, None
J. Walston, None
R. Rios, None
S. Leng, None