Primary central nervous system lymphoma: Comprehension of cell-of-origin subtypes

Primary central nervous system diffuse large B-cell lymphoma (PCNS-DLBCL) is an uncommon extranodal lymphoma that accounts for more than 95% of all the CNS lymphomas. Unlike its systemic/nodal counterpart, which is currently subtyped into cell-of origin (COO) subtypes, its feasibility and utility are largely debatable in PCNS-DLBCL. Objectives: To classify PCNS-DLBCL into COO-subtypes based on immunohistochemical algorithms by Hans and Choi and evaluate concordance between the two. A further aim is to investigate the clinicoradiological and histomorphological parameters of the subtypes thus obtained. Materials and Methods: As many as 143 cases of primary CNS lymphoma were evaluated by immunohistochemistry for CD10, BCL6, MUM1, GCET, and FOXP1 and based on which the said 143 cases were further classified into COO subtypes using Hans and Choi algorithms. Results: Mean age was 53.8 years with marginal male preponderance and predominantly centroblastic morphology (75.5%). CD 10 was positive in 8.9% of the cases, BCL6 in 58.6%, MUM1 in 89.9%, GCET in 32.9%, and FOXP1 in 79.5%. As much as 84.9% cases were of non-germinal center B-cell (GCB) subtype and 15.1% cases were of GCB subtype as determined based on Hans algorithm. Furthermore, 90.7% cases were of activated B-cell (ABC) subtype and 9.3% cases were of GCB subtype according to Choi algorithm. A 91.8% concordance was observed between Hans and Choi algorithms. Among the 6 discordant cases, 5 cases were subtyped as GCB by Hans and ABC by Choi and 1 case as ABC by Hans and GCB by Choi. Conclusion: Most of PCNS-DLBCLs are of non-GCB/ABC COO subtype, but inconsistences abound in the utility of IHC algorithms in PCNS-DLBCL COO subtypes.

Triptolide regulates the balance of Tfr/Tfh in lupus mice

Abstract Introduction/objectives Systemic lupus erythematosus (SLE) is a classic prototype of the multisystem autoimmune disease and follows a relapsing and remitting course. Triptolide is a diterpene triepoxide extracted from Chinese medicine Tripterygium wilfordii Hook F, with potent immunosuppressive and anti-inflammatory properties. Our previous work observed that triptolide alleviated lupus in MRL/lpr lupus mice with the upregulation of regulatory T cells (Treg) proportion in previous study. In this study, we explored the proportion of follicular T regulatory (Tfr), follicular T helper (Tfh) and germinal center (GC) B cells in lupus mice and evaluated the efficacy of triptolide for lupus treatment in vivo. Methods 20 female MRL/lpr mice were randomly divided into 2 treatment groups and treated orally with vehicle or triptolide. C3H mice were all housed as controlled group and treated orally with vehicle. The percentage of Tfr cells, Tfh cells and GC B cells in spleen of mice were detected by Flow cytometric analysis and immunohistochemistry after 13 weeks of treatment. Results We found that the percentage of Tfr cells decreased in MRL/lpr mice compared with controlled mice. The percentage of Tfh cells in MRL/lpr mice was significantly higher compared with that in controlled mice. The ratio of Tfr/Tfh is also decreased in lupus mice. After treated with triptolide in MRL/Lpr mice in vivo, the percentage of Tfr cells and ratio of Tfr/Tfh increased. The proportion of GC B cells also decreased in mice treated with triptolide by FACS and immunohistochemistry. Conclusions Our results demonstrate that the effect of triptolide in alleviating lupus is partly by reversing immune imbalance with increased percentage of Tfr cells and ratio of Tfr/Tfh. Triptolide might also has effect on immune response through inhibiting proliferating GC B cells.

Human follicular helper T lymphocytes critical players in antibody responses / Linfócitos T auxiliares foliculares humanos: células essenciais para a resposta de anticorpos

ABSTRACT Follicular helper T lymphocytes are a subpopulation of CD4+ T lymphocytes initially identified in germinal centers of follicles found in secondary lymphoid organs. The primary function of follicular helper T lymphocytes is to help B lymphocytes' antibody production. Changing of antibody class and affinity, B cell differentiation and memory generation depend on cooperation between follicular helper T lymphocytes and B cells. In blood, follicular helper T lymphocytes are called circulating follicular helper T lymphocytes. They are considered to have specificities similar to those developed in the secondary lymphoid organs. The phenotype of human follicular helper T lymphocytes is given by simultaneous expression of the markers CXCR5, Bcl-6, CD40L, PD-1, and ICOS. In germinal centers, follicular helper T lymphocytes synthesize interleukin 21 as predominant cytokine. In blood, subpopulations of circulating follicular helper T lymphocytes can be recognized, with different expressions of the classical follicular helper T lymphocytes markers and, in addition, can express other markers such as CXCR3 and CCR6. Presently, there is great interest in follicular helper T lymphocytes and circulating follicular helper T lymphocytes in vaccination studies as indicators of immunization efficacy. In addition, follicular helper T lymphocytes are investigated as possible markers of activity in many diseases and potential therapeutic intervention. This short review describes aspects of immunobiology and quantification of follicular helper T lymphocytes and circulating follicular helper T lymphocytes, and presents a few examples of related findings in systemic lupus erythematosus, rheumatoid arthritis, HIV infection and vaccination.

RESUMO Linfócitos T auxiliares foliculares são uma subpopulação de linfócitos T CD4+ identificada inicialmente nos centros germinativos dos folículos dos órgãos linfoides secundários. Sua função primordial é auxiliar os linfócitos B na produção de anticorpos. A mudança de classe e de afinidade dos anticorpos, a diferenciação das células B e a geração de memória dependem da cooperação entre os linfócitos T auxiliares foliculares e as células B. No sangue, recebem o nome de linfócitos T auxiliares circulantes. Considera-se que possuem especificidades semelhantes às desenvolvidas nos órgãos linfoides secundários. O fenótipo dos linfócitos T auxiliares humanos é dado pela expressão conjunta dos marcadores CXCR5, Bcl-6, CD40L, PD-1 e ICOS. Nos folículos, linfócitos T auxiliares sintetizam a interleucina 21 como citocina predominante. No sangue, são descritas várias subpopulações de linfócitos T auxiliares circulantes com expressões variadas dos marcadores clássicos de linfócitos T auxiliares, além de poderem agregar outros, como CXCR3 e CCR6. Existe um enorme interesse no estudo de linfócitos T auxiliares e linfócitos T auxiliares circulantes, para a avaliação de eficácia de vacinação. São também investigados como possíveis marcadores de atividade em muitas doenças e potenciais intervenções terapêuticas. Esta breve revisão descreve aspectos da imunobiologia e da quantificação de linfócitos T auxiliares humanos e linfócitos T auxiliares circulantes, além de apresentar alguns achados relacionados em lúpus eritematoso sistêmico, artrite reumatoide, infecção por HIV e vacinação.

Research Advances in Follicular Regulatory T Cells in Ocular Myasthenia Gravis / 中国医学科学院学报

Myasthenia gravis(MG)is a B cell-mediated,T cell-dependent,complements-involved autoimmune disease.Ocular myasthenia gravis(OMG)is a typical MG,with its symptoms limited to the extraocular muscles.The occurrence and development of a variety of autoimmune diseases including OMG are closely associated with the imbalanced expression of follicular regulatory T cells(Tfr cells).Therefore,Tfr cells may be a new research topic for OMG.

Immunophenotypic characteristics of diffuse large b-cell lymphoma and expression of C-MYC protein: single Ecuadorian center experience / Características inmunofenotípicas del linfoma difuso de células grandes B y expresión de la proteína C-MYC: experiencia en un centro de Ecuador

Abstract Background: Diffuse large B-cell lymphoma (DLBCL) makes up from 25% to 40% of all non-Hodgkin lymphomas (NHL) and is the most common histological subtype worldwide. In Ecuador, DLBCL makes up 49% of all NHL cases, but there have been no studies on the immunophenotypic classificationof DLBCL in germinal center (GC) and non-germinal center (NGC)subtypes.This study was conducted to ascertain the immunophenotypic profile of DLBCL in an Ecuadorian hospital. Methods: A total of 38 DLBCL cases from 2006 to 2015 were compiled from the Pathology Service at Metropolitan Hospital (HM) in Quito, Ecuador. Eleven of these cases failed to meet the inclusion criteria; thus, the final sample consisted of 27 cases. Manual tissue microarrays were constructed, and three immunohistochemical markers (CD10, BCL6, and MUM1) were applied according to the Hans algorithm; in addition, the expression of the c-myc protein expression was also investigated. Results: The results showed that 77.8% of cases were of the GC subtype, 11.1% were NGC, and 11.1% were unclassifiable according to the Hans algorithm. Conclusions: The most frequent DLBCL subtype was GC, with 21 cases; and 40.7% of these cases overexpressed c-myc.

Resumen Antecedentes: El linfoma difuso de células grandes B (LDCGB) constituye el 25 al 40% del total de los linfomas no Hodgkin (LNH) y es el subtipo histológico más frecuente en el mundo. En Ecuador el LDCGB corresponde al 49% del total de los casos de LNH, sin embargo no hay estudios de clasificación inmunofenotípica del LDCGB en centro germinal (CG) y no centro germinal (NCG). Este estudio se realizó para conocer el perfil inmunofenotípico del LDCGB en un hospital de Ecuador. Métodos: Se recopiló del Servicio de Patología del Hospital Metropolitano de Quito, Ecuador, un total de 38 casos de LDCGB desde el 2006 al 2015, de los cuales 11 no cumplieron con los criterios de inclusión. La muestra final fue de 27 casos. Se realizaron microarreglos tisulares manuales para la aplicación de tres marcadores de inmunohistoquímica según el algoritmo de Hans (CD10, BCL6 y MUM1) y luego se correlacionó con la sobreexpresión de la proteína c-MYC. Resultados: El 77,8% de casos fue tipo CG, 11,1% fue NCG y 11,1% fueron inclasificables según Hans. Conclusiones: El subtipo de LDCGB más frecuente fue CG con 21 casos y de estos 40,7% sobreexpresaron c-MYC.

Chromatin remodeling factor lymphoid-specific helicase links with Epstein-Barr virus associated the follicular germinal center B cell lymphomas

Background: We assessed the frequency of epigenetic lesions, including lymphoid-specific helicase (LSH), 5-hydroxymethylcytosine (5-hmC) and E2F1, and the possible correlations among molecular findings, phenotype, clinical features, and outcome. Methods: We investigated 181 paraffin-embedded B-cell lymphoma samples using immunohistochemistry and in situ hybridization. Results: The levels of Ki67, LSH, 5-hmC, and E2F1 were all increased in germinal center B-cell lymphomas when compared with those in normal lymph nodes, and LSH was highly expressed in diffuse large B-cell lymphomas (DLBCLs) and Burkitt lymphomas (BLs) that were positive for Epstein-Barr virus (EBV) infection, indicating that LSH is linked to EBV infection in DLBCL and BL. Interestingly, LSH was mainly localized in the germinal centers of lymph nodes whereas 5-hmC staining localized to areas surrounding the germinal centers. Conclusions: These findings indicate a critical role for LSH as a biomarker and therapeutic target in follicular germinal center B-cell lymphoma.

Enhancement of T Follicular Helper Cell-Mediated Humoral Immunity Reponses During Development of Experimental Autoimmune Myasthenia Gravis / 神经科学通报·英文版

Myasthenia gravis (MG) is a prototypical antibody-mediated neurological autoimmune disease with the involvement of humoral immune responses in its pathogenesis. T follicular helper (Tfh) cells have been implicated in many autoimmune diseases. However, whether and how Tfh cells are involved in MG remain unclear. Here, we established and studied a widely-used and approved animal model of human MG, the rat model with acetylcholine receptor alpha (AChRα) subunit (R-AChR)-induced experimental autoimmune myasthenia gravis (EAMG). This model presented mild body-weight loss 10 days after the first immunization (representing the early stage of disease) and more obvious clinical manifestations and body-weight loss 7 days after the second immunization (representing the late stage of disease). AChR-specific pre-Tfh cells and mature Tfh cells were detected in these two stages, respectively. In co-cultures of Tfh cells and B cells, the number of IgG2b-secreting B cells and the level of anti-AChR antibodies in the supernatant were higher in the cultures containing EAMG-derived Tfh cells. In immunohistochemistry and immunofluorescence assays, a substantial number of CD4/Bcl-6 T cells and a greater number of larger germinal centers were observed in lymph node tissues resected from EAMG rats. Based on these results, we hypothesize that an AChR-specific Tfh cell-mediated humoral immune response contributes to the development of EAMG.

Role of immunoreactive patterns of lymph nodes in neck dissection cases of oral squamous cell carcinoma: a clinical and histopathological study

OBJECTIVES: Metastasis in oral squamous cell carcinoma (OSCC) can occur in a variety of ways, and draining lymphatics and lymph nodes serve as a common route. Prior to metastasis, lymph nodes elicit an immune response to either wall off or create a favorable environment for homing of tumor cells. This immune response to tumor stimuli is visualized by recognizing various immunoreactive patterns exhibited by the lymph node. The present study aims to evaluate the role of immuno-morphologic patterns of the lymph node in neck dissection for cases of OSCC. MATERIALS AND METHODS: Our retrospective study included 50 neck dissection cases of OSCC and a total of 1,078 lymph nodes. The grades of primary tumors with eight different immunoreactive patterns were compared. Vascularity and metastasis in lymph nodes were also evaluated. RESULTS: The lymphocyte predominant pattern was the most common immunoreactive pattern found in 396 of 1,078 lymph nodes. Patterns of lymphocyte predominant (P=0.0005), sinus histiocytosis (P=0.0500), paracortical hyperplasia (P=0.0001), cortical hyperplasia (P=0.0001), and increased vascularity (P=0.0190) were significantly associated with tumor grade. CONCLUSION: The present study adds to the understanding of lymph node immunoreactivity patterns and their correlation with tumor grade. We recommend further study of lymph node patterns for all sentinel lymph node biopsies and routine neck dissections for OSCCs.

MicroRNA-mediated Regulation of the Development and Functions of Follicular Helper T cells

The germinal center reaction is a key event of humoral immunity, providing long-lived immunological memory. Follicular helper T (T(FH)) cells are a specialized subset of CD4⁺ T cells located in the follicles, which help B cells and thus control the germinal center reaction. T(FH) cell development is achieved by multi-step processes of interactions with dendritic cells and B cells along with the coordination of various transcription factors. Since the T helper cell fate decision program is determined by subtle changes in regulatory molecules, fine tuning of these dynamic interactions is crucial for the generation functional T(FH) cells. MicroRNAs (miRNAs) have emerged as important post-transcriptional regulatory molecules for gene expression, which consequently modulate diverse biological functions. In the last decade, the miRNA-mediated regulation network for the germinal center reaction has been extensively explored in T cells and B cells, resulting in the identification of several key miRNA species and their target genes. Here, we review the current knowledge of the miRNA-mediated control of the germinal center reaction, focusing on the aspect of T cell regulation in particular. In addition, we highlight the most important issues related to defining the functional target genes of the relevant miRNAs. We believe that the studies that uncover the miRNA-mediated regulatory axis of T(FH) cell generation and functions by defining their functional target genes might provide additional opportunities to understand germinal center reactions.

Enforced Expression of CXCR5 Drives T Follicular Regulatory-Like Features in Foxp3⁺ T Cells

CXCR5⁺ T follicular helper (Tfh) cells are associated with aberrant autoantibody production in patients with antibody-mediated autoimmune diseases including lupus. Follicular regulatory T (Tfr) cells expressing CXCR5 and Bcl6 have been recently identified as a specialized subset of Foxp3+ regulatory T (Treg) cells that control germinal center reactions. In this study, we show that retroviral transduction of CXCR5 gene in Foxp3⁺ Treg cells induced a stable expression of functional CXCR5 on their surface. The Cxcr5-transduced Treg cells maintained the expression of Treg cell signature genes and the suppressive activity. The expression of CXCR5 as well as Foxp3 in the transduced Treg cells appeared to be stable in vivo in an adoptive transfer experiment. Moreover, Cxcr5-transduced Treg cells preferentially migrated toward the CXCL13 gradient, leading to an effective suppression of antibody production from B cells stimulated with Tfh cells. Therefore, our results demonstrate that enforced expression of CXCR5 onto Treg cells efficiently induces Tfr cell-like properties, which might be a promising cellular therapeutic approach for the treatment of antibody-mediated autoimmune diseases.

Observation on destroyed architecture of splenic lymphoid follicles in mice infected with Schistosoma japonicum by immunohistochemistry / 中国血吸虫病防治杂志

Objective To observe the destroyed architecture of splenic lymphoid follicles in mice infected with Schistosoma japonicum by immunohistochemistry. Methods The mice infected with S. japonicum(20 cercariae/mouse)for 8 weeks were sacrificed,and the splenic samples were paraffin embedded and sliced. The sections were first stained by hematoxylin and eosin to observe the massive structure of splenic lymphoid follicles,and then B cells,follicular dendritic cells(FDC)and germinal center cells were labeled with anti-B220,anti-CD21 or anti-Ki67 antibodies respectively by immunohistochemistry to observe the distribution of the specific cells of lymphoid follicles. Results The results of HE staining showed that the structure of lym-phoid follicles in spleens of infected mice was blurred,the number and area of follicles were significantly reduced compared to those of the normal mice. The immunohistochemical staining showed that the splenic T/B lymphocyte segregation ,FDC network and germinal centers of the infected mice all disappeared. Conclusion The structure of splenic lymphoid follicles in the mice infected with S. japonicum is obviously damaged.

Interleukin-17 Enhances Germinal Center Formation and Immunoglobulin G1 Production in Mice

OBJECTIVE: Interleukin (IL)-17 is a pro-inflammatory cytokine that has pleiotropic effects on multiple target cells and thereby contributes to the development of immune-mediated inflammatory disorders. However, the role of IL-17 in the humoral immune response has not been clearly elucidated. METHODS: Mice deficient in IL-17A (IL-17A knockout [KO] mice) and wild type (WT) C57BL/6 mice were compared. Distinct B cell (mature/precursor and marginal zone/follicular) and plasma cell populations were compared using fluorescence-activated cell sorting (FACS) and confocal immunostaining. Immunoglobulin production was assessed by enzyme-linked immunosorbent assay. RESULTS: There was no difference in B cell and plasma cell populations between IL-17A KO and WT mice. However, after T cell-dependent antigen challenge, IL-17A KO mice produced lower levels of immunoglobulin (Ig)G1 than wild-type animals. IL-17A KO mice also showed reduced germinal center (GC) formation and lower expression of activation-induced cytidine deaminase, the essential enzyme for class switch recombination (CSR). IL-17 had no effect on the proliferation or survival of naïve B cells in in vitro functional studies. However, IL-17 treatment promoted naïve B cell differentiation into plasma cells in synergy with IL-4, although IL-17 alone had no effect. CONCLUSION: Our findings suggest that IL-17 contributes to the humoral immune response by enhancing GC formation, CSR to IgG1, and plasma cell differentiation in synergy with IL-4.

Mechanism of T follicular cells in experimental autoimmune encephalomyelitis / 中国免疫学杂志

Objective: To evaluate the mechanism of T follicular helper cells ( Tfh ) in experimental autoimmune encephalomyelitis (EAE) via in vivo experiments. Methods:C57BL/6 mice were randomly divided into four groups,CFA group,EAE group,anti-ICOSL group and control group. Lymphocytes of different time points isolated from draining lymph nodes and spleen were stained for T follicular helper cells surface marker and T cells activation surface marker and analyzed by FACS. Observed parameters include inflammatory infiltration,demyelination in spinal cord and germinal center in spleen. ELISA was used to measure the level of antigen specific antibodies. Results: Mice in anti-ICOSL treated group developed mild disease was with lower clinical scores when compared with the EAE group. HE staining results turned out with alleviated inflammation and Luxol Fast Blue staining( LFB) showed no demyelization in anti-ICOSL treated mice compared with non-treated EAE models. Flow cytometry results revealed that percentages of T follicular helper cells decreased though the whole activated degree T cells was not influenced in anti-ICOSL treated group. Fewer ger minal center was found in both anti-ICOSL group and CFA group with reduced secretion of MOG-specific Ab. Conclusion:T follicular helper cells supported the development of cognate B cells,promoted the formation of germinal center,facilitate pathogenic MOG-specific Ab secretion,thus enhance EAE.

The Significance of Ectopic Germinal Centers in the Minor Salivary Gland of Patients with Sjogren's Syndrome

We investigated the clinical and biological significance of germinal centers (GC) present in the minor salivary glands of patients with Sjogren's syndrome (SS). Minor salivary gland tissue biopsies from 93 patients with SS were used to identify GC-like structures, which were confirmed by CD21-positive follicular dendritic cell networks. Patients were compared based upon sociodemographics, glandular and extraglandular manifestations, and laboratory findings including autoantibody profiles, complement, and immunoglobulin levels; EULAR SS disease activity index (ESSDAI) and SS disease damage index (SSDDI) were also measured. GC-like structures were observed in 28 of 93 SS patients (30.1%). Mean focus scores and CRP levels were significantly higher in GC-positive patients than in GC-negative patients; GC-positive patients also exhibit a higher prevalence of rheumatoid factor and anti-SS-A/Ro antibodies compared to GC-negative patients. No differences in glandular or extra-glandular manifestations were evident between groups. In conclusion, SS patients with GC-like structures in the minor salivary glands exhibited laboratory profiles significantly different from those of their GC-negative counterparts. Long-term follow-up of these patients will be necessary to determine whether these laboratory abnormalities are predictive of clinical outcomes.

The Significance of Ectopic Germinal Centers in the Minor Salivary Gland of Patients with Sjogren's Syndrome

We investigated the clinical and biological significance of germinal centers (GC) present in the minor salivary glands of patients with Sjogren's syndrome (SS). Minor salivary gland tissue biopsies from 93 patients with SS were used to identify GC-like structures, which were confirmed by CD21-positive follicular dendritic cell networks. Patients were compared based upon sociodemographics, glandular and extraglandular manifestations, and laboratory findings including autoantibody profiles, complement, and immunoglobulin levels; EULAR SS disease activity index (ESSDAI) and SS disease damage index (SSDDI) were also measured. GC-like structures were observed in 28 of 93 SS patients (30.1%). Mean focus scores and CRP levels were significantly higher in GC-positive patients than in GC-negative patients; GC-positive patients also exhibit a higher prevalence of rheumatoid factor and anti-SS-A/Ro antibodies compared to GC-negative patients. No differences in glandular or extra-glandular manifestations were evident between groups. In conclusion, SS patients with GC-like structures in the minor salivary glands exhibited laboratory profiles significantly different from those of their GC-negative counterparts. Long-term follow-up of these patients will be necessary to determine whether these laboratory abnormalities are predictive of clinical outcomes.

Follicular Helper T (Tfh) Cells in Autoimmune Diseases and Allograft Rejection

Production of high affinity antibodies for antigens is a critical component for the immune system to fight off infectious pathogens. However, it could be detrimental to our body when the antigens that B cells recognize are of self-origin. Follicular helper T, or Tfh, cells are required for the generation of germinal center reactions, where high affinity antibody-producing B cells and memory B cells predominantly develop. As such, Tfh cells are considered as targets to prevent B cells from producing high affinity antibodies against self-antigens, when high affinity autoantibodies are responsible for immunopathologies in autoimmune disorders. This review article provides an overview of current understanding of Tfh cells and discusses it in the context of animal models of autoimmune diseases and allograft rejections for generation of novel therapeutic interventions.

Blockade of STAT3 in T Cells Inhibits Germinal Center Reactions against Intranasal Allergens

Understanding the developmental mechanisms of humoral immunity against intranasal antigens is essential for the development of therapeutic approaches against air-borne pathogens as well as allergen-induced pulmonary inflammation. Follicular helper T (Tfh) cells expressing CXCR5 are required for humoral immunity by providing IL-21 and ICOS costimulation to activated B cells. However, the regulation of Tfh cell responses against intranasal antigens remains unclear. Here, we found that the generation of Tfh cells and germinal center B cells in the bronchial lymph node against intranasal proteinase antigens was independent of TGF-β. In contrast, administration of STAT3 inhibitor STA-21 suppressed the generation of Tfh cells and germinal center B cells. Compared with wild-type OT-II T cells, STAT3-deficient OT-II T cells transferred into recipients lacking T cells not only showed significantly reduced frequency Tfh cells, but also induced diminished IgG as well as IgE specific for the intranasal antigens. Co-transfer study of wild-type OT-II and STAT3-deficient OT-II T cells revealed that the latter failed to differentiate into Tfh cells. These findings demonstrate that T cell-intrinsic STAT3 is required for the generation of Tfh cells to intranasal antigens and that targeting STAT3 might be an effective approach to ameliorate antibody-mediated pathology in the lung.

Regulatory T Cells in B Cell Follicles

Understanding germinal center reactions is crucial not only for the design of effective vaccines against infectious agents and malignant cells but also for the development of therapeutic intervention for the treatment of antibody-mediated immune disorders. Recent advances in this field have revealed specialized subsets of T cells necessary for the control of B cell responses in the follicle. These cells include follicular regulatory T cells and Qa-1-restricted cluster of differentiation (CD)8+ regulatory T cells. In this review, we discuss the current knowledge related to the role of regulatory T cells in the B cell follicle.

Influence of NK cell count on the survival of patients with diffuse large B-cell lymphoma treated with R-CHOP

BACKGROUND: Although adding rituximab to the chemotherapy regimen of cyclophosphamide, vincristine, doxorubicin, and prednisone (R-CHOP) has improved clinical outcomes of patients with diffuse large B-cell lymphoma (DLBCL), several recent studies have shown that the effect of rituximab is dominantly in the non-germinal center (non-GC) subtype compared to the germinal center (GC) subtype. Natural killer (NK) cell count, a surrogate marker of immune status, is associated with clinical outcomes in DLBCL patients in the rituximab era. We investigated whether the impact of NK cells on clinical outcomes differed according to the immunophenotype of DLBCL. METHODS: This study analyzed 72 DLBCL patients treated with R-CHOP between January 2010 and January 2014. RESULTS: Low NK cell counts (<100/microL) were associated with poor progression-free survival (PFS) and overall survival (OS) compared to high NK cell counts. In multivariate analysis, low NK cell count was an independent prognostic factor for PFS and OS. However, survival did not significantly differ between the GC and non-GC subtypes. We examined the clinical influence of NK cells according to the immunophenotype and found that low NK cell counts were significantly associated with poor PFS and OS in non-GC cases, but not in GC cases. CONCLUSION: Low NK cell counts at diagnosis are associated with poor clinical outcomes in DLBCL patients treated with R-CHOP therapy. However, the impact is significant only in non-GC subtype DLBCL, not in the GC subtype.

Insights into the Role of Follicular Helper T Cells in Autoimmunity

Follicular helper T (TFH) cells are recently highlighted as their crucial role for humoral immunity to infection as well as their abnormal control to induce autoimmune disease. During an infection, naive T cells are differentiating into TFH cells which mediate memory B cells and long-lived plasma cells in germinal center (GC). TFH cells are characterized by their expression of master regulator, Bcl-6, and chemokine receptor, CXCR5, which are essential for the migration of T cells into the B cell follicle. Within the follicle, crosstalk occurs between B cells and TFH cells, leading to class switch recombination and affinity maturation. Various signaling molecules, including cytokines, surface molecules, and transcription factors are involved in TFH cell differentiation. IL-6 and IL-21 cytokine-mediated STAT signaling pathways, including STAT1 and STAT3, are crucial for inducing Bcl-6 expression and TFH cell differentiation. TFH cells express important surface molecules such as ICOS, PD-1, IL-21, BTLA, SAP and CD40L for mediating the interaction between T and B cells. Recently, two types of microRNA (miRNA) were found to be involved in the regulation of TFH cells. The miR-17-92 cluster induces Bcl-6 and TFH cell differentiation, whereas miR-10a negatively regulates Bcl-6 expression in T cells. In addition, follicular regulatory T (TFR) cells are studied as thymus-derived CXCR5+PD-1+Foxp3+ Treg cells that play a significant role in limiting the GC response. Regulation of TFH cell differentiation and the GC reaction via miRNA and TFR cells could be important regulatory mechanisms for maintaining immune tolerance and preventing autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Here, we review recent studies on the various factors that affect TFH cell differentiation, and the role of TFH cells in autoimmune diseases.