Moderate Aerobic Exercise Induces Homeostatic IgA Generation in Senile Mice.

A T-cell-independent (TI) pathway activated by microbiota results in the generation of low-affinity homeostatic IgA with a critical role in intestinal homeostasis. Moderate aerobic exercise (MAE) provides a beneficial impact on intestinal immunity, but the action of MAE on TI-IgA generation under senescence conditions is unknown. This study aimed to determine the effects of long-term MAE on TI-IgA production in young (3 month old) BALB/c mice exercised until adulthood (6 months) or aging (24 months). Lamina propria (LP) from the small intestine was obtained to determine B cell and plasma cell sub-populations by flow cytometry and molecular factors related to class switch recombination [Thymic Stromal Lymphopoietin (TSLP), A Proliferation-Inducing Ligand (APRIL), B Cell Activating Factor (BAFF), inducible nitric oxide synthase (iNOS), and retinal dehydrogenase (RDH)] and the synthesis of IgA [α-chain, interleukin (IL)-6, IL-21, and Growth Factor-ß (TGF-ß)]; and epithelial cells evaluated IgA transitosis [polymeric immunoglobulin receptor (pIgR), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), IL-4] by the RT-qPCR technique. The results were compared with data obtained from sedentary age-matched mice. Statistical analysis was computed with ANOVA, and p < 0.05 was considered to be a statistically significant difference. Under senescence conditions, MAE promoted the B cell and IgA+ B cells and APRIL, which may improve the intestinal response and ameliorate the inflammatory environment associated presumably with the downmodulation of pro-inflammatory mediators involved in the upmodulation of pIgR expression. Data suggested that MAE improved IgA and downmodulate the cytokine pro-inflammatory expression favoring homeostatic conditions in aging.

Lymphoid follicular hyperplasia in patients with systemic lupus erythematosus after multiple cycles of rituximab.

Rituximab is indicated in some patients with refractory systemic lupus erythematosus (SLE). Occasionally, this medication is required in chronic form to maintain control of the disease. We described two patients who developed lymphoid follicular hyperplasia (LFH) after multiple cycles of rituximab and evaluated the expression of B cell activating factor belonging to the tumor necrosis factor (TNF) family (BAFF) and its receptors [BAFF-receptor (BAFF-R) and B cell maturation antigen (BCMA)], as possible factors related to lymphoid node enlargement. Two patients with SLE completed six and nine cycles of rituximab (1 g every 2 weeks) indicated each 9 months, achieving remission for 5 and 7 years, respectively, when developed prominent lymphadenopathies. Biopsies showed LFH. Haematological neoplasms were ruled out. Immunohistochemistry showed BAFF overexpression in the follicles, and moderate expression of BAFF-R confined to the mantle zone and BCMA to the germinal centre. Belimumab B cell activating factor belonging to the TNF family (anti-BAFF therapy) was started with positive effects on the clinical condition. LFH can develop in patients with SLE who received multiple cycles of rituximab. BAFF overexpression and moderate expression of BAFF-R and BCMA in lymph nodes were seen. These findings added to the improvement with the change to belimumab could suggest that LFH after cluster of differentiation (CD20) depletion therapy may be associated with a compensatory overexpression of BAFF and its receptors.

B-cell activating factor (BAFF) and its receptors' expression in pediatric nephrotic syndrome is associated with worse prognosis.

AIM: Immune pathogenesis of nephrotic syndrome (NS) is not completely understood. We aimed to evaluate the expression of B-cell activating factor (BAFF) and its receptors in renal samples from pediatric NS patients and its relationship with renal function survival. MATERIALS AND METHODS: We conducted an ambispective study on 33 patients with pediatric NS. Immunohistochemistry for BAFF, TACI, BCMA and BR3 was performed. Markers were evaluated on podocytes and interstitial inflammatory infiltrates (III). We performed Kaplan-Meier curves to describe renal function survival according to markers' expression. RESULTS: Thirty-three NS patients were included. Minimal change disease was seen in 21 (63.6%) patients, and focal segmental glomerulosclerosis in 12 (36.4%). BAFF was found in podocytes (18.2% of samples) and III (36.4% of samples), BAFF-R in one sample, TACI in 4 (podocytes and III), and BCMA in 5 samples of podocytes and 7 of III. BAFF on podocytes and III was associated with worst renal function at follow-up; those patients had 25% probability of having GFR >90 mL/min/1.73m2, versus 84.9% when absent (p = 0.0067). Patients with BAFF in III had 42.9% probability of having GFR>90 mL/min/1.73 m2, versus 94.1% when absent (p = 0.0063). CONCLUSION: BAFF expression in renal biopsies could be a prognostic factor for renal function.

Expression of BAFF and BAFF receptors in primary Sjögren's syndrome patients with ectopic germinal center-like structures.

B cell-activating factor (BAFF) is an essential cytokine in primary Sjögren's syndrome (pSS) physiopathology. It has been reported that pSS patients develop germinal center-like (GC-like) structures in their minor salivary glands (MSGs). BAFF, BAFF-R, TACI, and BCMA expression was analyzed in MSGs from 29 subjects (nonspecific chronic sialadenitis and focal lymphocytic sialadenitis with the presence [pSS-GC(+)] or absence [pSS-GC(-)] of GC-like structures). Twenty-four percent of patients showed ectopic GC-like structures and a high focus score [p < 0.001 vs pSS-GC(-)]. BAFF serum levels (sBAFF) were high in pSS patients (p = 0.025 vs healthy subjects). However, the pSS-GC(-) group showed higher sBAFF levels than pSS-GC(+) patients. BAFF and BAFF-R glandular expression levels were higher in pSS-GC(+) patients, without significant differences compared to pSS-GC(-) patients. Soluble levels of BAFF correlated with anti-La/SSB antibodies and disease duration. Our results showed that BAFF could contribute to focal lymphocytic infiltration. The role of BAFF-binding receptors in MSGs is proposed as a mechanism for the possible establishment of ectopic GC-like structures and disease progression in some patients. In conclusion, this study supports previous evidence that considers the active BAFF system role in the pathogenesis of pSS and the need for strong biomarkers in this disease.

B-cell profile, B-cell activating factor concentration and IgG levels in human cutaneous and mucosal leishmaniasis.

AIMS: The aim of this study was to evaluate characteristics of B cells in human tegumentary leismaniasis (TL) analysing cutaneous leishmaniasis (CL), most prevalent form and mucosal leishmaniasis (ML), aggressive form characterized by the destruction of the oral-nasal-pharyngeal cavities. METHODS AND RESULTS: By flow cytometry analysis, we found decreased percentages of non-class-switched memory B cells in TL with the degree of the loss related to clinical severity. Using commercial ELISA, we reported high levels of B-cell activating factor (BAFF) and IgG preferentially in aggressive CL and markedly in ML together with decreased BAFF receptors in the latter. We also found lower levels of BAFF after clinical recovery suggesting a relation between BAFF and disease activity. Mucosal leishmaniasis history of therapeutic failure presented high levels of BAFF accompanied by detectable concentrations of IFN-γ and IL-6 (assayed by commercial ELISA and cytometric bead arrays respectively), cytokines involved in exaggerated inflammatory responses and tissue damage in TL. CONCLUSION: We demonstrate B-cell disturbances in TL with the degree of the alterations related to clinical severity. We suggest a relation between excess of BAFF and disease activity and point towards a possible implication of BAFF in the inflammatory phenomenon of ML.

BAFF-R and TACI expression on CD3+ T cells: Interplay among BAFF, APRIL and T helper cytokines profile in systemic lupus erythematosus.

BACKGROUND: Systemic lupus erythematosus (SLE) is the prototype of systemic autoimmune disease, characterized by loss of immune tolerance against self-antigens where autoantibody production is the hallmark of disease. B-cell-activating factor (BAFF) and A proliferation-inducing ligand (APRIL) are cytokines that promote autoreactive cell survival, immunoglobulin-class switching and autoantibody responses in human and mouse SLE models. BAFF and APRIL exert their functions through interactions with their receptors BAFF-R and TACI that are differentially expressed in B lymphocyte subsets, monocytes, dendritic cells and T lymphocytes. BAFF stimulation favors T lymphocyte activation and cytokine production through BAFF-R, which could contribute to the Th1, Th17 and/or Th2 response dysregulation observed in SLE patients. OBJECTIVE: To evaluate the expression of the cytokines BAFF and APRIL and their association with the receptors BAFF-R and TACI on CD3+ T cells and to evaluate Th1/Th2/Th17 cytokine profile in patients with SLE. METHODS: Fifteen healthy controls (HC) and 36 SLE patients were included, and their demographic and clinical data were assessed. The disease activity index (Mex-SLEDAI) and damage index (SLICC) were applied to the SLE patients. BAFF-R and TACI expression on CD3+ T cells were evaluated by flow cytometry. Serum BAFF and APRIL concentrations were measured by enzyme-linked immunosorbent assays (ELISA). Cytokine levels of Th1 (IL-12, IL-2, IFN-γ, TNF-α), Th2 (IL-4, IL-6, IL-10, IL-13) and Th17 (IL-1ß e IL-17) were quantified with a multiplex assay (MAGPIX). Statistical analysis was performed using PASW Statistics v.20 and GraphPad Prism v.6 software. RESULTS: No differences in BAFF-R or TACI expression on the CD3+ T cells of SLE and HC were observed. BAFF-R expression correlates inversely with disease activity (r = -0.538, p < 0.01), while TACI correlates with disease activity (r = 0.530, p < 0.05). Serum BAFF and APRIL levels were high in SLE patients and correlated with the disease activity index Mex-SLEDAI (r = 0.621, p < 0.01 and r = 0.416, p < 0.05). SLE patients were found to have significantly higher levels of IL-12, IFN-γ, TNF-α, IL-6, IL-10, IL-13, IL-1ß and IL-17 compared to HC (p < 0.05). Cytokines IL-17 (r = 0.526) and TNF-α (r = 0.410) correlate with disease activity (p < 0.05), while APRIL (r = 0.477), IL-10 (r = 0.426) and IFN-γ (r = 0.440) levels were associated with organ damage (p < 0.01). Serum BAFF expression levels correlate with IL-4 (r = 0.424; p < 0.05), IL-6 (r = 0.420; p < 0.05) and IL-10 (r = 0.459; p < 0.01), whereas APRIL levels correlate with IL-2 (r = 0.666; p < 0.01), IL-12 (r = 0.611; p < 0.01) and TNF-α (r = 0.471; p < 0.05) cytokines. A subgroup of SLE patients with high serum BAFF levels (>2 ng/mL) also showed increased APRIL, IL-2, IL-6 and IL-10 levels (p < 0.05). Finally, BAFF, IL-4 and TNF-α serum levels were associated with high titers of antinuclear antibodies. CONCLUSIONS: The study demonstrates an imbalance in the Th1/Th2 cytokine profile, with increased proinflammatory cytokines, as well as BAFF and APRIL serum levels. Associations of BAFF with Th2 profile cytokines and disease activity, as well as APRIL with Th1 profile cytokines and organ damage, suggest that BAFF and APRIL generated in the autoimmunity context could through still unknown mechanisms, modulate the microenvironment, and perpetuate the inflammatory response, autoantibody production and organ damage observed in SLE patients.

Regulatory T-Cell Distribution within Lung Compartments in COPD.

The importance of the adaptive immune response, specifically the role of regulatory T (Treg) cells in controlling the obstruction progression in smokers, has been highlighted. To quantify the adaptive immune cells in different lung compartments, we used lung tissues from 21 never-smokers without lung disease, 22 current and/or ex-smokers without lung disease (NOS) and 13 current and/or ex-smokers with chronic obstructive pulmonary disease (COPD) for histological analysis. We observed increased T, B, IL-17 and BAFF+ cells in small and large airways of COPD individuals; however, in the NOS, we only observed increase in T and IL-17+ cells only in small airways. A decrease in the density of Treg+, TGF-ß+ and IL-10+ in small and large airways was observed only in COPD individuals. In the lymphoid tissues, Treg, T,B-cells and BAFF+ cells were also increased in COPD; however, changes in Treg inhibitory associated cytokines were not observed in this compartment. Therefore, our results suggest that difference in Treg+ cell distributions in lung compartments and the decrease in TGF-ß+ and IL-10+ cells in the airways may lead to the obstruction in smokers.

Association between IL-17 and IgA in the joints of patients with inflammatory arthropathies.

BACKGROUND: Hyperactive secretion and pathogenic effects of interleukin (IL)-17 and IgA have been detected in different arthropathies. Recent evidence has revealed that TH17 cytokines regulate mucosal IgA secretion. However, it is unknown whether and how IL-17 mediates synovial IgA production. Here we aim to investigate the connection of synovial IL-17 with IgA production in the joint. In this study we included synovial fluids (SF) from patients with rheumatoid arthritis (RA; n = 66), spondyloarthritis (SpA; n = 18) and osteoarthritis (OA; n = 36). The levels of IL-17, IL-6, transforming growth factor (TGF)-ß1, B-cell-activating factor of the TNF family (BAFF) and anti-lipopolyssacharide (LPS) immunoglobulin (Ig)A were investigated by enzyme-linked immunosorbent assay (ELISA). Total IgA was measured by radial immunodiffusion assay. Synovial fluid-derived mononuclear cells (SFMC) were stimulated with bacterial antigens or SF-conditioned media, and cytokines and IgA were analyzed in the supernatants. RESULTS: IL-17, IL-6 and TGF-ß1 were increased in SF from both RA and SpA compared with OA patients. Concentration of IL-17 correlated with the disease activity score (DAS)-28, IL-6 and anti-LPS IgA levels. Bacterial-stimulated SFMCs from RA and SpA patients secreted higher IL-17 than vehicle-stimulated SFMCs. Conditioned media with SF containing IL-17 induced anti-LPS IgA production by SFMCs which was independent of IL-6 activity. Concentrations of synovial TGF-ß1 and BAFF correlated with anti-LPS and total IgA levels, respectively. Blockade of IL-17 decreased the production of TGF-ß1 and anti-LPS IgA by SF-stimulated SFMCs. CONCLUSIONS: This study reports a connection between IL-17 and IgA secretion in the joint. In addition, it demonstrates that enterobacterial antigens trigger synovial IL-17 production, and that TGF-ß1 and BAFF may mediate the effect of IL-17 on IgA production. This circuit may contribute to the pathogenesis of inflammatory joint diseases.

Hormonal Modulation of Dendritic Cells Differentiation, Maturation and Function: Implications for the Initiation and Progress of Systemic Autoimmunity.

Hormonal homeostasis is crucial for keeping a competent and healthy immune function. Several hormones can modulate the function of various immune cells such as dendritic cells (DCs) by influencing the initiation of the immune response and the maintenance of peripheral tolerance to self-antigens. Hormones, such as estrogens, prolactin, progesterone and glucocorticoids may profoundly affect DCs differentiation, maturation and function leading to either a pro-inflammatory or an anti-inflammatory (or tolerogenic) phenotype. If not properly regulated, these processes can contribute to the pathogenesis of autoimmune disease. An unbalanced hormonal status may affect the production of pro-inflammatory cytokines, the expression of activating/inhibitory receptors and co-stimulatory molecules on conventional and plasmacytoid DCs (pDCs), conferring susceptibility to develop autoimmunity. Estrogen receptor (ER)-α signaling in conventional DCs can promote IFN-α and IL-6 production and induce the expression of CD40, CD86 and MHCII molecules. Furthermore, estrogen modulates the pDCs response to Toll-like receptor ligands enhancing T cell priming. During lupus pathogenesis, ER-α deficiency decreased the expression of MHC II on pDCs from the spleen. In contrast, estradiol administration to lupus-prone female mice increased the expression of co-stimulatory molecules, enhanced the immunogenicity and produced large amounts of IL-6, IL-12 and TNF-α by bone marrow-derived DCs. These data suggest that estradiol/ER signaling may play an active role during lupus pathology. Similarly, understanding hormonal modulation of DCs may favor the design of new therapeutic strategies based on autologous tolerogenic DCs transfer, especially in sex-biased systemic autoimmune diseases. In this review, we discuss recent data relative to the role of different hormones (estrogen, prolactin, progesterone and glucocorticoids) in DC function during systemic autoimmune pathogenesis.

A 3'UTR polymorphism marks differential KLRG1 mRNA levels through disruption of a miR-584-5p binding site and associates with pemphigus foliaceus susceptibility.

Genetic variations mapping to 3' untranslated regions (3'UTRs) may overlap with microRNA (miRNA) binding sites, therefore potentially interfering with translation inhibition or messenger RNA (mRNA) degradation. The aim of this study was to investigate whether single nucleotide polymorphisms (SNPs) located within the 3'UTRs of six candidate genes and predicted to interfere with miRNA ligation could account for disease-relevant differential mRNA levels. Focusing on pemphigus foliaceus (PF) - an autoimmune blistering skin condition with unique endemic patterns - we investigated whether nine 3'UTR SNPs from the CD1D, CTLA4, KLRD1, KLRG1, NKG7, and TNFSF13B genes differentially expressed in PF were disease-associated. The heterozygous genotype of the KLRG1 rs1805672 polymorphism was associated with increased predisposition to PF (A/G vs. A/A: P=0.038; OR=1.60), and a trend for augmented susceptibility was observed for carriers of the G allele (P=0.094; OR=1.44). In silico analyses suggested that rs1805672 G allele could disrupt binding of miR-584-5p, and indicated rs1805672 as an expression Quantitative Trait Locus (eQTL), with an effect on KLRG1 gene expression. Dual-luciferase assay showed that miR-584-5p mediated approximately 50% downregulation of the reporter gene's activity through the 3'UTR of KLRG1 harboring rs1805672 A allele (vs. miRNA-negative condition, P=0.006). This silencing relationship was lost after site-directed mutation to G allele (vs. miRNA-negative condition, P=0.391; vs. rs1805672 A allele, P=0.005). Collectively, these results suggest that a disease-associated SNP located within the 3'UTR of KLRG1 directly interferes with miR-584-5p binding, allowing for KLRG1 mRNA differential accumulation, which in turn may contribute to pathogenesis of autoimmune diseases, such as pemphigus.

Expression of BAFF and BR3 in patients with systemic lupus erythematosus

The objective of this study was to examine the relationship between the expression of B cell activating factor (BAFF) and BAFF receptor in patients with disease activity of systemic lupus erythematosus (SLE). Real-time RT-PCR was used to examine BAFF mRNA expression in peripheral blood monocytes of active and stable SLE patients and healthy controls. The percentage of BAFF receptor 3 (BR3) on B lymphocytes was measured by flow cytometry. Soluble BAFF levels in serum were assayed by ELISA. Microalbumin levels were assayed by an automatic immune analysis machine. BAFF mRNA and soluble BAFF levels were highest in the active SLE group, followed by the stable SLE group, and controls (P<0.01). The percentage of BR3 on B lymphocytes was downregulated in the active SLE group compared with the stable SLE group and controls (P<0.01). BAFF mRNA levels and soluble BAFF levels were higher in patients who were positive for proteinuria than in those who were negative (P<0.01). The percentage of BR3 on B lymphocytes was lower in patients who were positive for proteinuria than in those who were negative (P<0.01). The BAFF/BR3 axis may be over-activated in SLE patients. BAFF and BR3 levels may be useful parameters for evaluating treatment.

Expression of BAFF and BR3 in patients with systemic lupus erythematosus.

The objective of this study was to examine the relationship between the expression of B cell activating factor (BAFF) and BAFF receptor in patients with disease activity of systemic lupus erythematosus (SLE). Real-time RT-PCR was used to examine BAFF mRNA expression in peripheral blood monocytes of active and stable SLE patients and healthy controls. The percentage of BAFF receptor 3 (BR3) on B lymphocytes was measured by flow cytometry. Soluble BAFF levels in serum were assayed by ELISA. Microalbumin levels were assayed by an automatic immune analysis machine. BAFF mRNA and soluble BAFF levels were highest in the active SLE group, followed by the stable SLE group, and controls (P<0.01). The percentage of BR3 on B lymphocytes was downregulated in the active SLE group compared with the stable SLE group and controls (P<0.01). BAFF mRNA levels and soluble BAFF levels were higher in patients who were positive for proteinuria than in those who were negative (P<0.01). The percentage of BR3 on B lymphocytes was lower in patients who were positive for proteinuria than in those who were negative (P<0.01). The BAFF/BR3 axis may be over-activated in SLE patients. BAFF and BR3 levels may be useful parameters for evaluating treatment.

Increase in multiple sclerosis activity after assisted reproduction technology.

OBJECTIVE: Our objective was to evaluate risk of exacerbations in multiple sclerosis (MS) patients undergoing assisted reproduction technology (ART) infertility treatment. METHODS: Sixteen patients with relapsing-remitting MS subjected to 26 ART treatment cycles receiving gonadotropin-releasing hormone (GnRH) agonists and recombinant follicle-stimulating hormone were studied prospectively. The baseline study period encompassed 12 months prior to the first cycle and 9 months after final ART cycle. Neurological examinations, brain magnetic resonance imaging (MRI), and immunology testing were conducted every 3 months. Anti-myelin-oligodendrocyte glycoprotein (MOG) antibody production, interleukin (IL)-4, IL-8, IL-10, IL-12, IL-17, interferon (IFN)-γ, and transforming growth factor (TGF)-ß secretion by myelin basic protein- and MOG-peptide-specific T cells, as well as ex vivo isolated peripheral blood mononuclear cells (PBMCs), were studied using enzyme-linked immunospot. vascular endothelial growth factor (VEGF) production by PBMCs was assessed using enzyme-linked immunosorbent assay. RESULTS: ART was associated with a 7-fold increase in risk of MS exacerbation, and a 9-fold increase in risk of enhanced disease activity on MRI. Worsening was associated with higher number of cells producing IL-8, IL-12, IFN-γ, and TGF-ß, as well as increased VEGF production by CD4(+) T cells and CXCL-12 plasma levels, all GnRH-mediated effects. A rise in 17-ß estradiol production associated with ART increased anti-MOG antibody titers, as well as B-cell survival factor BAFF (B-cell activating factor) and antiapoptotic molecule Bcl-2 levels from purified CD19(+) B cells. Finally, ART facilitated PBMC transmigration across an in vitro blood-brain barrier model, an effect mediated by IL-8, VEGF, and CXCL-12. INTERPRETATION: Results indicate a significant increase in MS disease activity in patients receiving ART, a risk that neurologists should be aware of. Reproductive hormones appear to exert an important role in regulating immune responses during the course of autoimmune diseases.

BAFF mediates splenic B cell response and antibody production in experimental Chagas disease.

BACKGROUND: B cells and antibodies are involved not only in controlling the spread of blood circulating Trypanosoma cruzi, but also in the autoreactive manifestations observed in Chagas disease. Acute infection results in polyclonal B cell activation associated with hypergammaglobulinemia, delayed specific humoral immunity and high levels of non-parasite specific antibodies. Since TNF superfamily B lymphocyte Stimulator (BAFF) mediates polyclonal B cell response in vitro triggered by T. cruzi antigens, and BAFF-Tg mice show similar signs to T. cruzi infected mice, we hypothesized that BAFF can mediate polyclonal B cell response in experimental Chagas disease. METHODOLOGY/PRINCIPAL FINDINGS: BAFF is produced early and persists throughout the infection. To analyze BAFF role in experimental Chagas disease, Balb/c infected mice were injected with BR3:Fc, a soluble receptor of BAFF, to block BAFF activity. By BAFF blockade we observed that this cytokine mediates the mature B cell response and the production of non-parasite specific IgM and IgG. BAFF also influences the development of antinuclear IgG and parasite-specific IgM response, not affecting T. cruzi-specific IgG and parasitemia. Interestingly, BAFF inhibition favors the parasitism in heart. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate, for the first time, an active role for BAFF in shaping the mature B cell repertoire in a parasite infection.

[BAFF: A regulatory cytokine of B lymphocytes involved in autoimmunity and lymphoid cancer]. / BAFF: Una citoquina reguladora de linfocitos B implicada en autoinmunidad y cáncer linfoide.

BAFF (B cell activating factor belonging to the TNF family) is a cytokine implicated in the survival and maturation of peripheral B lymphocytes and T and B cell activation. BAFF binds to three different receptors: TACI, BCMA and BAFF-R, whose expression is restricted to B and T lymphocytes. BAFF and BAFF-R-deficient mice show a dramatic loss of peripheral B lymphocytes and a severely reduced immune response. In contrast, an enhanced BAFF expression leads to B cell hyperplasia and autoimmunity in mice. In vivo, administration of soluble decoy receptors for BAFF effectively decreases disease progression in various autoimmune mouse models. These evidences render BAFF as a potentially new therapeutic target. Elevated BAFF levels have been detected in the serum of patients with autoimmune diseases, such as Systemic Lupus Erythematosus, rheumatoid arthitis, Sjögren's syndrome, lymphoid cancers and HIV infection. In addition to BAFF receptors, malignant B cells abnormally express BAFF, which attenuates apoptosis through both autocrine and paracrine pathways. The data suggest that an increase in the expression of BAFF induces an enhanced B and T cell activation and the survival of pathologically active B cells. In this article, we review and discuss the participation of BAFF and its receptors in the immune response and its involvement in immunodeficiency, autoimmunity, infections and lymphoid cancers as well as the currently investigated therapies using BAFF antagonists in the treatment of these diseases.

BAFF: Una citoquina reguladora de linfocitos B implicada en autoinmunidad y cáncer linfoide / BAFF: A regulatory cytokine of B lymphocytes involved in autoimmunity and lymphoid cancer

BAFF (B cell activating factor belonging to the TNF family) is a cytokine implicated in the survival and maturation of peripheral B lymphocytes and T and B cell activation. BAFF binds to three different receptors: TACI, BCMA and BAFF-R, whose expression is restricted to B and T lymphocytes. BAFF and BAFF-R-deficient mice show a dramatic loss of peripheral B lymphocytes and a severely reduced immune response. In contrast, an enhanced BAFF expression leads to B cell hyperplasia and autoimmunity in mice. In vivo, administration of soluble decoy receptors for BAFF effectively decreases disease progression in various autoimmune mouse models. These evidences render BAFF as a potentially new therapeutic target. Elevated BAFF levels have been detected in the serum of patients with autoimmune diseases, such as Systemic Lupus Erythematosus, rheumatoid arthitis, Sjõgren's syndrome, lymphoid cancers and HIV infection. In addition to BAFF receptors, malignant B cells abnormally express BAFF, which attenuates apoptosis through both autocrine and paracrine pathways. The data suggest that an increase in the expression of BAFF induces an enhanced B and T cell activation and the survival of pathologically active B cells. In this article, we review and discuss the participation of BAFF and its receptors in the immune response and its involvement in immunodeficiency, autoimmunity, infections and lymphoid cancers as well as the currently investigated therapies using BAFF antagonists in the treatment of these diseases.