Phenotype of neoplastic cells in angioimmunoblastic T-cell lymphoma is consistent with activated follicular B helper T cells

Abstract

We have hypothesized that neoplastic T cells may be related to follicular B helper T (T_FH) cells,^3-6 since CD10⁺ atypical T cells were found to be in intimate contact with the expanded meshwork of proliferating follicular dendritic cells (FDCs), a characteristic of AITL. Therefore, we have performed consecutive double immuno-labeling to analyze expression of some known T_FH cell functional antigens (CXCR5, CD154/CD40L, CD134/OX40, and CD57) in the CD10⁺ T cells in 20 paraffin-embedded AITL cases. Since Kim et al⁷ and Chtanova et al⁸ established that CXCL13 is highly up-regulated in T_FH cells, expression of this antigen was also investigated; the same has also been done by Grogg et al.¹