Immune checkpoint expression on lymphocyte populations in head and neck cancer patients

Introduction:

Immune evasion is one of the major mechanisms for uncontrolled proliferation and migration of tumor cells. Amongst others, natural control mechanisms such as immune checkpoints are exploited to dampen the anti-neoplastic immune response. The blockade of these inhibitory signal pathways with checkpoint inhibitors already shows clinical benefits in cancer treatment.

Methods:

Peripheral blood lymphocytes (PBL) and tumor infiltrating lymphocytes (TIL) were isolated from healthy controls (n = 20) and HNSCC (head and neck squamous cell carcinoma) patients (n = 22) and in vitro stimulated. Expression of 9 immune-checkpoints was analyzed by flow cytometry. Differences between immune-checkpoint expression of stimulated and unstimulated as well as differences between healthy donors and tumor patients were investigated. Expression patterns in TIL were compared to PBL.

Results:

Stimulation of the lymphocytes led to an upregulation of the majority of analyzed immune checkpoints on lymphocyte sub-populations (CD4+, CD8+, Treg, B-cells). Different lymphocyte populations of cancer patients show higher PD-1 expression as healthy donors. Frequency of lymphocyte subpopulations shows significant differences between PBL and TIL. Specific immune checkpoint expression patterns could be determined in TIL compared to PBL.

Conclusion:

Activated lymphocytes show a specific change of immune checkpoint expression. These results contribute to a better understanding of immune checkpoint function on lymphocytes. The finding of specific immune checkpoint expression on lymphocytes in the tumor microenvironment may help to improve immunotherapeutic approaches.

Publication History

Publication Date:
18 April 2018 (online)