Mass Cytometry of Follicular Lymphoma Tumors Reveals Intrinsic Heterogeneity in Proteins Including HLA‐DR and a Deficit in Nonmalignant Plasmablast and Germinal Center B‐Cell Populations

Abstract

Background Follicular lymphoma (FL) is an indolent non-Hodgkin lymphoma that has a risk of transformation to more aggressive lymphoma. Relatively little is known about the non-malignant B-cell and T-cell subset composition within the tumor microenvironment and whether altered phenotypes are associated with patterns of lymphoma B-cell heterogeneity. Methods Two mass cytometry (CyTOF) panels were designed to immunophenotype B and T cells in FL tumors. Populations of malignant B cells, non-malignant B cells, and T cells from each FL tumor were identified and their phenotypes compared to B and T cells from healthy human tonsillar tissue. Results Diversity in cellular phenotype between tumors was greater for the malignant B cells than for non-malignant B or T cells. The malignant B-cell population bore little phenotypic similarity to any healthy B-cell subset, and unexpectedly clustered closer to naïve B-cell populations than GC B-cell populations. Among the non-malignant B cells within FL tumors, a significant lack of GC and plasmablast B cells was observed relative to tonsil controls. In contrast, non-malignant T cells in FL tumors were present at levels similar to their cognate tonsillar T-cell subsets. Conclusion Mass cytometry revealed that diverse HLA-DR expression on FL cells within individual tumors contributed greatly to tumor heterogeneity. Both malignant and non-malignant B cells in the tumor bore little phenotypic resemblance to healthy GC B cells despite the presence of T follicular helper cells in the tumor. These findings suggest that ongoing signaling interactions between malignant B cells and intra-tumor T cells shape the tumor microenvironment.

Preparing Viable Single Cells from Human Tissue and Tumors for Cytomic Analysis

“…Our group and others have implemented this technology in studies of donor and patient cells that are obtained as a suspension, such as blood and bone marrow (Bendall et al, 2011; Hardy et al, 1983; Kordasti et al, 2016; Leelatian et al, 2015; Nicholas et al, 2016; Parks et al, 1984; Qiu et al, 2011; Tung et al, 2004) or that can be disaggregated from lymphoid structures by mechanical force alone (Irish et al, 2006a; Irish et al, 2010; Myklebust et al, 2016; Polikowsky et al, 2015; Wogsland et al, 2016). Clinical diagnoses of blood malignancies use fluorescence flow cytometry characterization of cell surface marker expression, as well as cell subset quantification (Arber et al, 2016; Craig and Foon, 2008; van Dongen et al, 2012; Wood et al, 2007).…”

From the Editor: Thank you! Remembrances and Issue Highlights

“…The initial contribution by Seegmiller, His and Craig [(3) & cover article] is a review of flow cytometry in the evaluation of mature B-cell neoplasms, a topic of regular interest to our readership as evidenced by these recent publications (3)(4)(5)(6)(7)(8). This is a joint effort of the ICCS and our Society's own Sa Wang and the Society of Hematopathology, represented by Magdalena Czader.…”

Integrated functional and mass spectrometry-based flow cytometric phenotyping to describe the immune microenvironment in acute myeloid leukemia

“…These limitations make the expanded panels available in mass cytometry appealing for complex hematologic evaluations. Due to this advantage, several groups have used mass cytometry to assess the cellular and immune make up in patients with heme malignancies including lymphoma (Wogsland et al, 2017), multiple myeloma (Baughn et al, 2017), and CML (Gullaksen et al, 2017; Bandyopadhyay et al, 2017) (Table 1). …”