Impaired cellular immune response to diphtheria and tetanus vaccines in children after thoracic transplantation.

Safety and immunogenicity of diphtheria and tetanus booster vaccination were evaluated in 28 children after thoracic transplantation. Adverse events were documented in a patient diary. Blood was collected prior to and four wk after vaccination. Specific antibody concentrations were measured by ELISA. Lymphocytes were investigated for expression of activation markers (CD25, HLA-DR) by flow cytometry and proliferation assays with and without stimulation. Post-vaccination antibody titers were higher than prevaccination (p < 0.001), with more patients having protective antibody levels against diphtheria (p < 0.02) and tetanus (p < 0.001). There was no increased proliferation in non-stimulated or stimulated cultures after vaccination. The number of T-lymphocytes activated by the vaccination antigens was similar pre- and post-vaccination, whereas HLA-DR-expression on stimulated and non-stimulated CD4(+) T-cells increased significantly. Increase in antibodies was negatively correlated with tacrolimus dose, and impaired cellular immunity was associated with higher tacrolimus dose and steroid use. Adverse events were similar to the general population; serious adverse events and rejection did not occur. Vaccination with inactivated vaccines can be performed safely in immunosuppressed children after thoracic transplantation and induces protective antibody levels in the majority of patients. Impaired induction of specific cellular immunity is correlated with intensity of immunosuppression and may explain reduced sustainability of antibodies.