Foxp3+ regulatory T (Treg) cells suppress different types of immune responses to help maintain homeostasis in the body. How Treg cells regulate humoral immunity, including germinal center reactions, is unclear. Here we identify a subset of Treg cells expressing CXCR5 and Bcl6, and localized in the germinal centers in mouse as well as human. The expression of CXCR5 on Treg cells depends on Bcl6. These CXCR5+Bcl6+ Treg cells are absent in thymus but can be de novo generated from CXCR5-Foxp3+ natural Treg precursors. Lack of CXCR5+ Treg cells leads to greater germinal center reactions. These results unveil a Bcl6-CXCR5 axis in Treg cells that undermines the development of follicular regulatory T (Tfr) cells that function to inhibit the germinal center reaction.

Summary Background Standard treatments for indolent non-Hodgkin lymphomas (iNHLs) are frequently toxic, and most patients ultimately relapse. Lenalidomide, an immunomodulatory agent, is effective as monotherapy for relapsed iNHL. The aim of this phase 2 trial (NCT00695786) was to evaluate the efficacy and safety of lenalidomide plus rituximab in untreated, advanced-stage iNHL and determine the combinaton’s effect on the immune system and tumour microenvironment. The primary objective was to determine the number of complete and partial responses. Methods For follicular lymphoma (FL) and marginal zone lymphoma (MZL), lenalidomide was given orally at 20 mg/day on days 1–21 of all 28-day cycles. Dosing for small lymphocytic lymphoma (SLL) began at 10 mg/day to avoid tumour flare. Rituximab was given at 375 mg/m2 body surface area on day 1 of each cycle. Patients responding after 6 cycles could continue therapy for up to 12 cycles. Patients were evaluated for response analysis if they had any post-baseline tumor assessment. Findings The study enrolled 110 patients, and 103 were evaluable for efficacy analysis. All patients were eligible for safety analysis. The most common grade 3 or 4 adverse events were neutropenia (35%), muscle pain (9%), rash (7%), cough/dyspnea (7%), fatigue (5%), thrombosis (5%), and thrombocytopenia (4%). The overall response rate was 90% (93/103) (95% confidence interval [CI] 83–95%). Complete and partial response rates were 63% (95% CI 53–72%) and 27% (95% CI 19–37%), respectively. Eighty-seven percent (95% CI 74–95%) and 11% (95% CI 4–24%) of FL patients achieved complete and partial responses, respectively. Seventy-nine percent of evaluable FL patients remained in remission at 36 months. Interpretation Lenalidomide plus rituximab is well tolerated and highly effective as initial treatment for iNHL. Durable response rates obtained without cytotoxic agents suggest this regimen could replace chemotherapy as the frontline treatment of iNHL. An international phase 3 study (NCT01476787) is ongoing comparing this regimen to chemotherapy in untreated follicular lymphoma. Funding The study was funded by Celgene Corporation and the Richard Spencer Lewis Memorial Foundation.

The microenvironment of human follicular lymphoma (FL), an incurable B-cell non-Hodgkin lymphoma, is thought to play a major role in its pathogenesis and course. Microenvironmental cells of likely importance include follicular helper T cells (TFH) and regulatory T cells (Tregs), and understanding their interactions with FL tumor cells is necessary to develop novel therapeutic strategies. We found that IL-4 and CD40L are expressed by intratumoral TFH and induce production of CCL17 and CCL22 by FL tumor cells. IL-4 alone induces only CCL17, but enhances stimulation by CD40L of both CCL17 and CCL22. Consistent with our in vitro results, mRNA transcripts of IL-4 correlated with CCL17 but not CCL22 in gene expression profiling studies of FL biopsies, whereas CD40L correlated with both CCL17 and CCL22. Tumor supernatants induced preferential migration of Tregs and IL-4–producing T cells rather than IFN-γ–producing T cells, and antibodies to CCR4 significantly abrogated the migration of Tregs. Our results suggest that through two distinct mechanisms, intratumoral TFH induce production of CCL17 and CCL22 by FL tumor cells and facilitate active recruitment of Tregs and IL-4–producing T cells, which in turn may stimulate more chemokine production in a feed-forward cycle. Thus, TFH appear to play a major role in generating an immunosuppressive tumor microenvironment that promotes immune escape and tumor survival and growth. Our results provide novel insights into the cross talk between TFH, tumor cells, and Tregs in FL and offer potential targets for development of therapeutic strategies to overcome immune evasion.

Antigen activation of the B-cell receptor (BCR) may play a role in the pathogenesis of human follicular lymphoma (FL) and other B-cell malignancies. However, the nature of the antigen(s) recognized by tumor BCRs has not been well studied. Here, we used unbiased approaches to demonstrate that 42 (19.35%) of 217 tested FL immunoglobulins (Igs) recognized vimentin as a shared autoantigen. The epitope was localized to the N-terminal region of vimentin for all vimentin-reactive tumor Igs. We confirmed specific binding to vimentin by using recombinant vimentin and by performing competitive inhibition studies. Furthermore, using indirect immunofluorescence staining, we showed that the vimentin-reactive tumor Igs colocalized with an anti-vimentin monoclonal antibody in HEp-2 cells. The reactivity to N-terminal vimentin of IgG FL Igs was significantly higher than that of IgM FL Igs (30.4% vs. 10%; P=0.0022). However, vimentin-reactive FL Igs did not share complimentarity determining region 3 motifs and were not homologous. Vimentin was expressed in the T-cell rich regions of FL, suggesting that vimentin is available for binding with tumor BCRs within the tumor microenvironment. Vimentin was also frequently recognized by mantle cell lymphoma and multiple myeloma Igs. Our results demonstrate that vimentin is a shared autoantigen recognized by nonstereotyped FL BCRs and by the Igs of mantle cell lymphoma and multiple myeloma and suggest that vimentin may play a role in the pathogenesis of multiple B-cell malignancies. These findings may lead to better understanding of the biology and natural history of FL and other B cell malignancies.

Immunotherapy with therapeutic idiotype vaccines offers promise for treatment of B-cell malignancies. However, identification of novel immunogenic lymphomaassociated antigens that are universally expressed is necessary to overcome the barriers of patient-specific idiotype vaccines. Here, we determined whether T-cell leukemia/lymphoma 1 (TCL1) oncoprotein encoded by the TCL1 gene could be a target for immunotherapy of B-cell malignancies. We show that TCL1 mRNA and protein are selectively expressed in normal B cells but markedly hyperexpressed in multiple human B-cell lymphomas, including follicular lymphoma, chronic lymphocytic leukemia, mantle cell lymphoma, diffuse large B-cell lymphoma, and splenic marginal zone B-cell lymphoma. We demonstrated that TCL1-specific CD8 ؉ T cells can be generated from HLA-A*0201 (HLA-A2) ؉ normal donors and identified TCL1 [71][72][73][74][75][76][77][78] IntroductionMalignancies of B-cell origin are highly responsive to combination chemotherapy, and complete remissions can be induced in most patients. The use of rituximab, an anti-CD20 monoclonal antibody, in combination with chemotherapy has improved the overall and complete response rates, progression-free survival, overall survival, and curability of patients with B-cell non-Hodgkin lymphomas. [1][2][3] However, relapse remains a significant cause of treatment failure, and novel treatments are needed to eradicate minimal residual disease to further improve clinical outcome in these patients.Therapeutic agents used to eradicate minimal residual disease should ideally be directed at different targets and have different mechanisms of action than agents used in induction therapy. They also should be safe with minimal adverse effects because they may need to be administered as maintenance therapy over several months. Therapeutic vaccines have many of these desirable features because they can target different antigens on the lymphoma tumor cells than those targeted by rituximab or chemotherapy agents, and they are safe and well tolerated. 4 Furthermore, by inducing immunologic memory and polyclonal humoral and cellular immune responses, vaccines may potentially produce a sustained antitumor effect, and unlike monoclonal antibodies, they may prevent the emergence of antigen-loss variants. Thus, therapeutic vaccines against lymphomas can be complementary to passive immunotherapeutic agents such as monoclonal antibodies and cytotoxic chemotherapeutic agents and could be ideal for eradicating minimal residual disease.Several groups have used the clonal tumor immunoglobulin expressed on the surface of mature B-cell malignancies, termed idiotype, as a tumor-specific antigen for development of therapeutic vaccines against lymphomas. [5][6][7][8][9][10][11] Idiotype vaccines were shown to be safe and induced sustained antitumor antibody and CD4 ϩ and CD8 ϩ T-cell responses in patients with follicular lymphoma (FL), chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MCL), and diffuse large B-cell lymphoma (DLBCL). [5][6][7][8][9][...