The Value of Immunological Methods in the Complex Diagnostics of TB in Chronic Renal Failure Patients in the Terminal Stage

Introduction: There is lack of data about the value of immunological methods in the diagnostics of TB in chronic renal failure (CRF) patients in the terminal stage, who are immunocompromised due to replacement therapy or kidney transplantation. Aim: To evaluate the value of immunological methods for TB diagnosis in CRF patients. Material and Methods: 34 CRF patients were included in the study (18 (53%) patients diagnosed for TB, 16 (47%) – for other diseases). Immunological analysis included: tuberculosis skin tests; QuantiFERON®-TB Gold Plus; T-SPOT®; the determination of Mtb-specific CD27-IFN-γ+ cells (“Mtb-CD27”), the evaluation of CD4+, CD8+, CD19+, CD16/CD56+ cells. Results: IGRAs showed low sensitivity (47%), but high specificity (93 and 94 %) and demonstrated higher concordance with the diagnosis (~70%) than skin tests (64%). Mtb-CD27 had high sensitivity (82%), but low specificity (13%). The latter was likely due to bystander stimulation of CD4+ lymphocytes in CRF patients leading to a high percentage of CD27- lymphocytes within CD4+ population. Flow cytometry analysis demonstrated lower counts of Mtb-specific IFN-γ-producing CD4 lymphocytes in TB patients with CRF compared to TB patients without CRF, which could account for low sensitivity of IGRAs. Conclusions: Immunological tests can be used in complex diagnostics of TB in patients with terminal stage of CRF, but their limitations should be taken into account. Low sensitivity of IGRAs can be explained by insufficient counts of Mtb-specific IFN-γ-producingCD4 lymphocytes. Low specificity of the Mtb-CD27 can be attributed to pronounced inflammation associated with CRF