Peripheral blood analysis by flow cytometry and gene expression profiling in long-term renal transplant recipients with squamous cell carcinoma

S. Bezstarosti, M.J. Bottomley, J. Hester, F. Issa

Thursday 5 march 2020

13:30 - 13:40h at Theaterzaal

Parallel session: Parallel sessie XII – Klinische en Basale abstracts

Background: The development of squamous cell carcinoma (SCC) is a major problem in renal transplant recipients (RTRs). In these patients, the increased risk of malignancy is associated with the use of immunosuppressive agents, an increased frequency of regulatory T cells (Tregs), and cellular exhaustion. This study aimed to identify a signature in the peripheral blood that is associated with SCC development after transplantation and which could contribute to the risk assessment of SCC in RTRs.

Methods: We used flow cytometry and multiplex gene expression profiling to analyse the peripheral blood mononuclear cells of 30 matched long-term RTRs with or without SCC incidence within a follow up period of five years. Different populations of Tregs and exhausted CD8+ and CD4+ T cells were identified and correlated with SCC development.

Results: The frequency of CD70-expressing Tregs was higher in RTRs with SCC development compared with patients who did not develop SCC. There was no difference in the frequency of total Tregs between these groups. Additionally, there was no difference in the expression of the exhaustion markers PD-1, TIGIT, LAG3 and TIM-3 by CD8+ or CD4+ T cells between RTRs with and without SCC development.

Conclusions: In this study we demonstrated that the frequency of CD70-expressing Tregs in RTRs that developed SCC within the follow-up period of five years is increased compared with patients without SCC development. The potential of CD70 as a clinical marker for the identification of patients with a high risk of SCC warrants further investigation.