Functional state of human spleen T cells in Marginal Zone Lymphoma

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Presentation Time: 03:15 PM - 04:30 PM
Poster Board Number: B138
Abstract ID: 5017

Presenting Author:
Saloni T Ramani , MS Student at Univ. of Rochester Sch. of Med. & Dent.

Abstract:

Splenic Marginal Zone Lymphoma (SMZL) is a rare, indolent B-cell Non-Hodgkin’s Lymphoma located mainly in the spleen. Increased expression of exhaustion markers on T cells has been described in SMZL. We have now analyzed the responsiveness of SMZL T cells to the polyclonal activator, Staphylococcal Enterotoxin B (SEB). De-identified cryo-preserved cells from 15 SMZL spleens, 10 Trauma (control) spleens and 5 healthy-donor PBMCs were analyzed by two 26-color flow cytometry panels testing the T cell phenotype, and expression of Activation-Induced Markers (AIM). We confirmed that SMZL CD8+ and CD4+ T cells had enhanced expression of exhaustion markers including CD279, CD278 and TIGIT. SMZL CD8+ and CD4+ T cells showed reduced proportions of AIM+ cells after SEB stimulation, compared to PBMC and controls. To determine whether the SMZL cells were inherently unresponsive or were deficient in co-stimulatory signals for SEB activation, SMZL cells were co-cultured with CFSE-labeled PBMC or control spleen cells. The proportions of SEB-induced AIM+ SMZL T cells were increased by co-culture with PBMC (and to a lesser extent, control spleen cells). Conversely, SMZL dampened PBMC activation in co-cultures. Our data suggest that the SMZL environment is deficient in co-stimulatory signals for T cell activation (e.g. MHC II or soluble mediators) or alternatively, that the SMZL environment includes suppressive effects that are diluted in co-culture (e.g. Treg cells or suppressive cytokines).