Follicular lymphoma (FL) derives from malignant transformation of germinal center (GC) B cells. FL malignant B cells are heterogeneous and diverge from their GC B cell-of-origin, but the diversity, function, and location of malignant B cell states remain to be addressed. Based on integrative single-cell RNA-seq, we identified and studied recurrent FL malignant B cell states and dynamics. Most FL B cells spanned a continuum of states from proliferating GC-like to quiescent memory (Mem)-like cell states. That GC-to-Mem axis was the main source of intra-tumor transcriptional heterogeneity. While FL B cell states were independent from subclonal B cell receptor genetics divergence, T follicular helper (TFH) cell-derived signals controlled the transition from Mem-like to GC-like states. GC-like, TFH-activated and Mem-like FL B cells tended to occupy distinct niches within and around tumor follicles. Our study characterizes novel malignant cell states recurrent in B cell lymphomas, and highlights the functional plasticity of malignant B cells.
Immunohistochemical (IHC) testing for HER2/neu is becoming the standard of care for guiding the adjuvant treatment of gastric carcinoma with trastuzumab. Up to now, gastric cancer has been considered the most commonly diagnosed tumors leading to death.In this study, we evaluate the detection of HER2 expression by IHC in Tunisian patients with gastric cancer according to the international consensus. A total of 84 tumor specimens was assessed for HER2 expression by immunohistochemistry (IHC) using the antibodies HercepTest™. Doubtful IHC results (IHC 2+) were resolved by HER2 Chromogenic in situ hybridization (CISH). Thus, 10.5% of samples were HER2-positive (3+), 8.3% having a negative score IHC, Her2-Neu (+1) and 3.6% to be a dubious immunostaining Her2-Neu (2+).
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