HLA‐DR allotype is associated with responsiveness to influenza vaccine in elderly Japanese

Background: Influenza virus infection is a serious problem in elderly people because of a high pneumonia complication rate and a significant increase in mortality. Influenza vaccine in the pre‐endemic period is effective in reducing these problems. The contribution of the major histocompatibility complex to the effectiveness of such vaccination is worth analysis. Methods: HLA‐DR types of 57 elderly Japanese people were determined after influenza vaccination. HLA‐DR types and responsiveness to the vaccine were defined in the subjects. Phytohemagglutinin (PHA) responsiveness was also determined. The association between HLA‐DR types and the responsiveness to the influenza vaccine was evaluated. Results: The HLA‐DR2 phenotype showed the most significant association with responsiveness to the influenza vaccine. The PHA response as a general immunological parameter for T cell function was not associated with responsiveness to the influenza vaccine. Conclusions: These findings suggest that HLA‐DR2 phenotype contributes to the enhancement the production of antibodies against the influenza virus in elderly Japanese people.