['The impact of influenza vaccination on in vitro parameters of cellular and humoral immunity, anti-viral titers, and clinical outcome was evaluated among cardiac transplant recipients.', 'Blood was collected from 29 patients before and 3-4 weeks after influenza vaccination and tested for phenotypic changes in lymphoid subpopulations and generation of antibodies against the allograft and vaccine.', 'Vaccination did not change the percentage of lymphoid subpopulations and did not induce generation of anti-HLA alloantibodies. Anti-vaccine response was detected in 12 of 29 patients and did not correlate with rejection history, length of graft survival, or immunosuppressive therapy. Vaccination did not change the frequency of rejection. Flu-like symptoms were reported in one patient but not confirmed microbiologically.'] Does influenza vaccination promote cellular or humoral activation among heart transplant recipients?