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Expression of programmed death-1 (CD279) in primary cutaneous B-cell lymphomas with correlation to lymphoma entities and biological behaviour

Authors


  • Funding sources None.
  • Conflicts of interest None declared.

Summary

Background

Programmed death-1 (PD-1/CD279) is a cell-surface protein expressed in activated T cells and a subset of T lymphocytes including follicular helper T cells (TFH). The interaction between PD-1 and its ligands plays a role in immune response and evasion of malignancies. In nodal follicular lymphoma, the number of intratumoral PD-1-positive lymphocytes is associated with overall survival.

Objectives

To investigate 28 cases of primary cutaneous B-cell lymphoma, including the subtypes PCFCL (= 10), PCMZL (= 10) and DLBCL-LT (= 8) for the number and density of PD-1-positive cells.

Methods

Immunohistochemical staining and a computerized morphometric analysis for evaluation were applied. The results were correlated with the clinical outcome. To distinguish between activated T cells and TFH we performed PD-1/bcl-6 double staining and compared these results with CXCL-13 staining. Double staining for PD-1 and PAX-5 was used to investigate whether tumour cells were positive for PD-1.

Results

The PD-1-positive cells represented tumour-infiltrating T cells (TILs). Only a minor subset was represented by TFH. Patients with DLBCL-LT had a significantly lower number of PD-1-positive TILs than those with PCMZL (= 0·012) and PCFCL (= 0·002) or both (= 0·001). The difference between PCMZL and PCFCL did not reach significance (= 0·074). The tumour cells were negative for PD-1.

Conclusions

A higher number of PD-1-expressing cells was found in indolent PCMZL and PCFCL than in high-malignant DLBCL-LT. The PD-1-positive cells represented not only TFH, but also other activated T cells as a part of the tumour microenvironment. The tumour cells in all investigated types of PCBCL did not show aberrant PD-1 expression.

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