Nodal T-cell lymphomas derived from the TFH cell show characteristic morphologic, clinical, and genetic alterations with numerous overlaps within subgroups. They are characterized by a TFH cell phenotype and a strong correlation with the microenvironment. TFH cells (TFH is the acronym for "follicular B helper T-cells") form a smaller subpopulation of Th lymphocytes that express CXCR5 on their surface. These cells are found within the B-cell follicles of human tonsils as well as in the blood.
CXCR5 (acronym for CXC motif chemokine receptor 5) is a receptor protein of the chemokine recept or family. This receptor type is found in particular on lymphocytes (B and T lymphocytes) and can be detected in particularly high density on cells of Burkitt's lymphoma. CXCR5 is activated by a cytokine, the CXC motif chemokine CXCL13 (BCA-1), and plays an important role in the targeted attraction (chemotaxis) of B cells.
The rare nPTCL with TPH phenotype are listed as a new independent entity in the 2017 revised WHO classification (see below peripheral T-cell lymphomas).