Incidence, Outcomes, and Long-term Immune Response to Tuberculosis in Organ Transplant Recipients

Background Tuberculosis (TB) is a significant opportunistic infection in solid organ transplant recipients (SOTR). There are limited data on TB incidence in transplantation from low prevalence countries as well as on long-term TB-specific immune responses. Methods We performed a single-center retrospective review of SOTR diagnosed with active TB between 2000 and 2015 and further contacted the available patients for a study of long-term T-cell responses using an interferon-gamma (IFN-γ) release assay and a flow cytometry-based assay. Results We identified 31 SOTR with active TB for an incidence of 62 cases/100 000 patient-years. Nineteen (61.3%) of 31 patients were diagnosed within the first year after transplant. Nineteen (61.3%) were born in countries with high TB prevalence and disseminated disease occurred in 22.6%. No patient had been screened for latent TB infection pretransplant. The majority of patients received isoniazid and a rifamycin as part of multidrug regimen. In addition, 13 (44.8%) of 29 patients received quinolones. One-year mortality in this population was 19.4%. Eight patients were available for long-term immune responses. Of these, all had detectable IFN-γ response by IFN-γ release assay testing and 7 of 8 had detectable TB-specific T cells, primarily central and effector T-cell responses in the CD4 compartment and terminally differentiated T cells in the CD8 compartment. Conclusions TB has high incidence in SOTR even in low-prevalence regions but especially targets patients who originated from TB-endemic countries. Long-term TB-specific T-cell responses were found in the majority of patients.