Tumour-Immune Microenvironment In Duodenal-Type Follicular Lymphoma

Despite duodenal-type follicular lymphoma (DTFL) being morphologically, immunophenotypically and genetically indistinguishable from nodal FL (nFL), this entity typically shows a significantly better prognosis. Here, we analysed the tumour immune microenvironments of diagnostic specimens from patients with DTFL (n = 30), limited-stage FL (LSFL; n = 19) and advanced-stage FL (ASFL; n = 31). The mean number of CD8(+) tumour-infiltrating lymphocytes (TILs) in the neoplastic follicles was higher in DTFL (1,827/mm(2)) than in LSFL (1,150/mm(2)) and ASFL (1,188/mm(2)) (P = 0 center dot 002, P = 0 center dot 002, respectively). In addition, CD8(+)PD1(-) T cells with non-exhausting phenotype were more abundant in the peripheral blood (PB) of DTFL than in LSFL and ASFL, indicating that DTFL may exhibit a better and longer-lasting T cell-mediated immune response. Moreover, whereas FOXP3(+)CTLA-4(+) effector regulatory T cells (eTregs) were rarely observed in the neoplastic follicles of DTFL (mean: 12/mm(2)), they were more abundant in LSFL (78/mm(2)) and ASFL (109/mm(2)) (P = 2 center dot 80 x 10(-5), P = 4 center dot 74 x 10(-8), respectively), and the numbers of eTregs correlated inversely with those of CD8(+) TILs (r = -0267; P = 0 center dot 018). Furthermore, DTFL showed significantly fewer circulating FOXP3(hi)CD45RA(-)CD25(hi) eTregs (0 center dot 146%) than ASFL (0 center dot 497%) and healthy controls (0 center dot 639%) (P = 0 center dot 0003, P = 6 center dot 79 x 10(-7), respectively). These results suggest that the augmented anti-tumour immune reactions may contribute to a better prognosis on DTFL.