PD-1 and PD-L1 in neoplastic cells and the tumor microenvironment of Merkel cell carcinoma

• Background: Merkel cell carcinoma (MCC) is an aggressive neoplasm, which is often associated with Merkel cell polyomavirus (MCPyV). Programmed death-1 (PD-1) and its ligand PD-L1 are key players of the tumor microenvironment (TME). Methods: Fourteen paraffin-embedded tissue samples of MCC were stratified by their MCPyV detection. Apart from PD-L1 and PD-1, the TME was further characterized for the expression of CD33, FOXP3 and MxA. Results: We observed PD-1 in 2 of 12 tumors. PD-L1 expression by tumor cells was found in 7 of 8 MCPyV(+) samples and was detected particularly in the periphery. The tumor cells were surrounded by a shield of PD-L1/CD33 immune cells. Expression of PD-L1 by the tumor cells was higher in areas with a denser immune infiltrate. CD33(+) cells without direct tumor contact were PD-L1 negative. Only a low number of FOXP3(+) regulatory T-cells was admixed. Tumor cells of MCPyV(−) samples were mostly PD-L1 negative. Conclusions: Our data demonstrate that PD-L1 expression occurs in tumor and immune cells, in areas in which they are close in contact. Interferon seems to play a role in this interaction. We postulate that PD-L1(+)/CD33(+) cells shield the tumor against attacking PD-1(+) immune cells. Therefore, next to anti-PD-1/PD-L1 antibodies, blockade of CD33 seems to be a promising therapeutic approach. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Hälsovetenskap -- Annan hälsovetenskap (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Health Sciences -- Other Health Sciences (hsv//eng)

Nyckelord

CD274 protein

human

PDCD1 protein

human

programmed death 1 ligand 1

programmed death 1 receptor

tumor marker

aged

female

human

immunology

male

merkel cell carcinoma

skin tumor

tumor associated leukocyte

tumor microenvironment

very elderly

Aged

Aged

80 and over

B7-H1 Antigen

Biomarkers

Tumor

Carcinoma

Merkel Cell

Female

Humans

Lymphocytes

Tumor-Infiltrating

Male

Programmed Cell Death 1 Receptor

Skin Neoplasms

Tumor Microenvironment

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art (ämneskategori)