Germinal center reentries of BCL2-overexpressing B cells drive follicular lymphoma progression
Stéphanie Sungalee, … , Bertrand Nadel, Sandrine Roulland
Stéphanie Sungalee, … , Bertrand Nadel, Sandrine Roulland
Published November 10, 2014
Citation Information: J Clin Invest. 2014;124(12):5337-5351. https://doi.org/10.1172/JCI72415.
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Germinal center reentries of BCL2-overexpressing B cells drive follicular lymphoma progression

Abstract

It has recently been demonstrated that memory B cells can reenter and reengage germinal center (GC) reactions, opening the possibility that multi-hit lymphomagenesis gradually occurs throughout life during successive immunological challenges. Here, we investigated this scenario in follicular lymphoma (FL), an indolent GC-derived malignancy. We developed a mouse model that recapitulates the FL hallmark t(14;18) translocation, which results in constitutive activation of antiapoptotic protein B cell lymphoma 2 (BCL2) in a subset of B cells, and applied a combination of molecular and immunofluorescence approaches to track normal and t(14;18)+ memory B cells in human and BCL2-overexpressing B cells in murine lymphoid tissues. BCL2-overexpressing B cells required multiple GC transits before acquiring FL-associated developmental arrest and presenting as GC B cells with constitutive activation–induced cytidine deaminase (AID) mutator activity. Moreover, multiple reentries into the GC were necessary for the progression to advanced precursor stages of FL. Together, our results demonstrate that protracted subversion of immune dynamics contributes to early dissemination and progression of t(14;18)+ precursors and shapes the systemic presentation of FL patients.

Authors

Stéphanie Sungalee, Emilie Mamessier, Ester Morgado, Emilie Grégoire, Philip Z. Brohawn, Christopher A. Morehouse, Nathalie Jouve, Céline Monvoisin, Cédric Menard, Guilhaume Debroas, Mustapha Faroudi, Violaine Mechin, Jean-Marc Navarro, Charlotte Drevet, Franziska C. Eberle, Lionel Chasson, Fannie Baudimont, Stéphane J. Mancini, Julie Tellier, Jean-Michel Picquenot, Rachel Kelly, Paolo Vineis, Philippe Ruminy, Bruno Chetaille, Elaine S. Jaffe, Claudine Schiff, Jean Hardwigsen, David A. Tice, Brandon W. Higgs, Karin Tarte, Bertrand Nadel, Sandrine Roulland

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Figure 1

The sporadic BCL2tracer model.

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The sporadic BCL2tracer model. (A) Germline and rearranged configuration...
(A) Germline and rearranged configuration of the BCL2tracer transgene by RAG-mediated inversion. Only the rearranged configuration allows the expression of a full-sized, functional huBCL2 oncoprotein. Recombination signal sequences (DH3-RSS, JH6RSS) are indicated by triangles. V(D)J-mediated coding joints (BCL2CJ) and signal joints are indicated. A representative F-PCR screen from a 3-month-old mouse shows the presence of the transgene in all replicates (3+4, bottom) and a sporadic clonotypic BCL2CJ rearrangement in a few replicates (1+2, top). The frequency of inversion is calculated using Poisson’s assumption based on the number of positive PCRs and input DNA. ex, exon; f, frequency. (B) BCL2CJ frequency evaluated by F-PCR in lymphoid organs and blood from 2- to 12-month-old BCL2tracer mice. Black lines represent the mean. *P < 0.05; **P < 0.01. (C) BCL2CJ follow-up with aging in blood at steady state. (D) BCL2CJ frequency in total spleen and cell-sorted B cell subpopulations from resting (white bars) and challenged mice (light and dark gray bars). Pooled splenocytes (3–5 mice) were used in each condition. NA, absent or too small to sort. (E) IHC of unchallenged or srbc-immunized BCL2tracer mice stained with B220 (pan-B), PNA (GC marker), and huBCL2 antibodies. A human spleen was used as a positive control for huBCL2 staining. PNA was used instead of GL7 (44) because of better staining intensity. Scale bar: 500 μm. (F) Immunization scheme and immunofluorescence (IF) microscopy of BCL2tracer spleen sections stained with IgD (blue), B220 (green), and huBCL2 (red) antibodies. IgD staining indicates GC boundaries. Arrows point to rare huBCL2+ cells. Scale bars: 100 μm (left panel), 20 μm (middle panels).