Purpose: Following the recommended consensus guidelines of ATC for vaccination, at our institution we recommend annual vaccination for influenza + H1N1 (Flu) for renal transplant recipients. However, impact of response on (Flu) antibody development in immunosuppressed patients was a concern. Therefore we tested the antibody response in a group of renal transplant recipients.

Methods: Forty-seven renal transplant recipients enrolled in an IRB approved study had samples drawn before and 4 – 8 weeks after standard Flu vaccination. Serum was frozen, stored, and tested in a batch assay by a commercial ELISA (Casaba Biotech Co.). Following manufacturers protocol, when OD/Negative Control optical density (OD) was greater than or equal to 2.1 the result was considered positive and if less than 2.1 result was negative. Patients received Thymoglobulin induction and maintenance immunosuppression of calcineurin inhibitors and mycophenolic acid, but were steroid free. In earlier testing using samples obtained at the same time points, HLA antibody testing was performed using single antigen luminex beads.

Results: Thirty patients were positive on the pre-vaccination sample 28 remained positive after vaccination and 2 tests were negative after vaccination. Seventeen were negative before vaccination, but only 3(17.6%) converted to positive after vaccination. The remaining fourteen that tested negative before vaccination remained negative after vaccination. Thirty-two showed an increase in OD when pre and post vaccination tests were compared 0.070±0.104 and 15 had a decrease in OD 0.062±0.060.No patients developed new DSA's or new non DSA HLA antibodies. No significant changes in the titers of preexisting HLA antibodies were observed post vaccination. No patients were found to have developed significant influenza disease.

Conclusion: There appears to be suboptimal response when using standard flu vaccine post-transplantation. A different Flu immunization regimen should be considered. A two-stage standard dose vaccinations or use of the available high dose vaccine may induce a greater antibody response.

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