NFkB location in T-cells is promising to monitor immunosuppression after lung transplantation

Background : In solid organ transplantation, immunosuppression (IS) by calcineurin inhibitors (CI) or mTOR inhibitors (mTORI) is assessed by blood levels, which do not reflect the biological activity towards effector cells (EC). The transcription factor nuclear factor kappa beta (NFkB) mediates cell survival, proliferation and growth arrest by regulation of cytokine and chemokine expression. Therefore, nuclear NFkB location (nNFkB-l) might mirror the activity of EC. Aims and objectives: We investigated if the nNFkB-l in T-cells represents a suitable parameter to monitor the biological activity of IS. Methods: n NFkB-l was analysed in unstimulated and TNF-a stimulated T-cells in 13 lung transplant recipients and 7 healthy controls by Multispectral Imaging Flow Cytometry. The results were linked to IS and clinical data. In parallel the number of IFN-g releasing peripheral blood cells (PBLs) after CD3/CD28 stimulation was defined by ELISpot. Results: An increased proportion of unstimulated or TNF-a stimulated CD8+ T-cells with nNFkB-l (mean±SEM %) was found in unstable patients e.g. with infections (35.1±7.4 or 45.9±7.2; N=5) compared to stable patients (19.0±3.2, p=0.02 or 30.4±2.7, p=0.06; N=8) or controls (19.3±4.2, p=0.03 or 31.9±3.61, p=0.1, N=7). A trend for higher nNFkB-l in CD8 cells was found in patients with mTORI (33.2±9.0; N=5) compared to CI treated patients (20.2±2.5, p=0.2; N=8). Regarding function, the number of IFN-g producing PBLs correlated with nNFkB-l in CD8 stimulated T-cells (r=0.69, p=0.002; N=17). Conclusion: These results provide first evidence that the nNFkB-l in T-cells might be a promising and functionally relevant tool to monitor IS after lung transplantation.