In vitro B cell experiments explore the role of CD24, CD38, and energy metabolism in ME/CFS

Introduction

Disturbances of energy metabolism contribute to the clinical manifestations of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Previously, we found that B cells from ME/CFS patients have an increased expression of CD24, a modulator of many cellular functions including those of cell stress. The relative ability of B cells from ME/CFS patients and healthy controls (HC) to respond to rapid changes in energy demand was compared.

Methods

CD24, the ectonucleotidases CD39 and CD73, the NAD-degrading enzyme CD38, and mitochondrial mass (MM) were measured following cross-linking of the B cell receptor and costimulation with either T-cell-dependent or Toll-like-receptor-9-dependent agonists. The levels of metabolites consumed/produced were measured using 1H-NMR spectroscopy and analyzed in relation to cell growth and immunophenotype.

Results

Proliferating B cells from patients with ME/CFS showed a lower mitochondrial mass and a significantly increased usage of essential amino acids compared with those from HC, with a significantly delayed loss of CD24 and an increased expression of CD38 following stimulation.

Discussion

The immunophenotype results suggested the triggering of a stress response in ME/CFS B cells associated with the increased usage of additional substrates to maintain necessary ATP levels. Disturbances in energy metabolism in ME/CFS B cells were thus confirmed in a dynamic in vitro model, providing the basis for further mechanistic investigations.

Disparity in peripheral and renal B-cell depletion with rituximab in systemic lupus erythematosus: an opportunity for obinutuzumab?

OBJECTIVES

To investigate key factors that may contribute to the variability of rituximab-mediated peripheral and renal B cell depletion (BCD) in SLE.

METHODS

We analysed: (i) CD19+ B cell counts in patients with SLE before and 1, 2, 3 and 6 months after treatment with rituximab, comparing them with RA patients; (ii) the presence of B cells in renal biopsies after rituximab therapy; (iii) whether the duration of BCD correlated with patient demographics and B cell expression of CD20 and FcγRIIb; and (iv) the effect of B cell activation factor (BAFF) on the efficiency of rituximab and obinutuzumab at inducing BCD in whole blood assays, in vitro.

RESULTS

In SLE (n = 71), the duration of BCD was shorter compared with RA (n = 27). B cells were detectable in renal biopsy samples (n = 6) after treatment with rituximab in all patients with poor response while peripheral blood B cells remained low or undetectable in the same patients. There were no significant relationships between peripheral BCD and patient age, disease duration, serum C3 levels or the level of expression of B cell surface proteins CD20 and FcγRIIb. Obinutuzumab was more efficient than rituximab at inducing BCD in whole blood assays, regardless of excess BAFF.

CONCLUSIONS

BCD in SLE is less efficient than in RA. Renal B cell presence following rituximab treatment was associated with poor outcomes. No significant relationships between any measured B cell related, clinical or laboratory parameters and the efficiency of BCD by rituximab was found. Obinutuzumab was superior to rituximab at inducing BCD.

Infections Related to Biologics: Agents Targeting B Cells

B cells are an essential component of the adaptive immune system. Since the late 1990s biologic drugs targeting B cells have been used to treat not only lymphoproliferative diseases of B-cell lineage cells but also autoimmune diseases, in particular, those associated with autoantibody production. Although some of these agents are relatively safe, they have been associated with serious infections including opportunistic infections. To what extent the infectious complications reported are directly related to the use of the B-cell targeting agent or to previous and/or concomitant immunosuppressive therapies and/or the specific disease being treated is often difficult to ascertain.

The lung in a cohort of rheumatoid arthritis patients-an overview of different types of involvement and treatment

OBJECTIVES

Lung involvement in RA has several manifestations and is a major cause of morbidity and mortality. The aim of this study was to characterize the different types of lung disease and response to treatment in a UK cohort of RA patients.

METHODS

RA patients who had undergone high resolution CT scans of the lung were identified and scans reviewed. Demographic data, RA features, complementary exams and treatments were recorded for those with radiological evidence of lung involvement. Descriptive analysis was performed, and Mann-Whitney U and χ2 tests were used for comparison between different radiological subtypes.

RESULTS

Lung disease was reported in 87 (7.7%) of 1129 RA patients, usually (97.7%) post-dating articular symptoms. Most patients had positive RF (74/84; 88.1%) and ACPA (72/82; 87.7%). Interstitial lung disease (ILD) was the most common pattern, reported in 45 (51.7%) patients. Drug-induced lung disease was reported in 2 of 64 (3.1%) patients treated with MTX. Rituximab was used in 26 (57.8%) patients with ILD, with evidence of disease improvement or stabilization in patients with non-specific interstitial pneumonia and organizing pneumonia. During lung disease follow-up (6.7 ± 4.1 years), 22 (25.3%) patients were admitted to hospital with respiratory infections, with 14 (63.6%) of them having underlying bronchiectasis. Lung disease-related mortality was estimated at 8%.

CONCLUSION

ILD was the most prevalent manifestation of lung involvement in RA and was associated with higher mortality. Immunosuppressive drugs used in RA were rarely associated with lung toxicity, and rituximab demonstrated promising results for the treatment of RA-ILD.

CD24 Expression and B Cell Maturation Shows a Novel Link With Energy Metabolism: Potential Implications for Patients With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

CD24 expression on pro-B cells plays a role in B cell selection and development in the bone marrow. We previously detected higher CD24 expression and frequency within IgD+ naïve and memory B cells in patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) compared with age-matched healthy controls (HC). Here, we investigated the relationship between CD24 expression and B cell maturation. In vitro stimulation of isolated B cells in response to conventional agonists were used to follow the dynamics of CD24 positivity during proliferation and differentiation (or maturation). The relationship between CD24 expression to cycles of proliferation and metabolism in purified B cells from HC was also investigated using phospho-flow (phosphorylation of AMPK-pAMPK), 1proton nuclear magnetic resonance and Mitotracker Far-red (Mitochondrial mass-MM). In vitro, in the absence of stimulation, there was an increased percentage of CD24+ viable B cells in ME/CFS patients compared to HC (p < 0.05) following 5 days culture. Following stimulation with B cell agonists, percentage of CD24+B cells in both naïve and memory B cell populations decreased. P < 0.01). There was a negative relationship between percentage of CD24+B cells with MM (R² = 0.76; p < 0.01), which was subsequently lost over sequential cycles of proliferation. There was a significant correlation between CD24 expression on B cells and the usage of glucose and secretion of lactate in vitro. Short term ligation of the B cell receptor with anti-IgM antibody significantly reduced the viability of CD24+ memory B cells compared to those cross-linked by anti-IgD or anti-IgG antibody. A clear difference was found between naïve and memory B cells with respect to CD24 expression and pAMPK, most notably a strong positive association in IgD+IgM+ memory B cells. In vitro findings confirmed dysregulation of CD24-expressing B cells from ME/CFS patients previously suggested by immunophenotype studies of B cells from peripheral blood. CD24-negative B cells underwent productive proliferation whereas CD24+ B cells were either unresponsive or susceptible to cell death upon BCR-engagement alone. We suggest that CD24 expression may reflect variations in energy metabolism on different B cell subsets.

Detection of Experimental and Clinical Immune Complexes by Measuring SHIP-1 Recruitment to the Inhibitory FcγRIIB

Fc γ receptors (FcγR) are involved in multiple aspects of immune cell regulation, are central to the success of mAb therapeutics, and underpin the pathology of several autoimmune diseases. However, reliable assays capable of accurately measuring FcγR interactions with their physiological ligands, IgG immune complexes (IC), are limited. A method to study and detect IC interactions with FcγRs was therefore developed. This method, designed to model the signaling pathway of the inhibitory FcγRIIB (CD32B), used NanoLuc Binary Interaction Technology to measure recruitment of the Src homology 2 domain-containing inositol phosphatase 1 to the ITIM of this receptor. Such recruitment required prior cross-linking of an ITAM-containing activatory receptor, and evoked luciferase activity in discrete clusters at the cell surface, recapitulating the known biology of CD32B signaling. The assay detected varying forms of experimental IC, including heat-aggregated IgG, rituximab-anti-idiotype complexes, and anti-trinitrophenol-trinitrophenol complexes in a sensitive manner (≤1 μg/ml), and discriminated between complexes of varying size and isotype. Proof-of-concept for the detection of circulating ICs in autoimmune disease was provided, as responses to sera from patients with systemic lupus erythematosus and rheumatoid arthritis were detected in small pilot studies. Finally, the method was translated to a stable cell line system. In conclusion, a rapid and robust method for the detection of IC was developed, which has numerous potential applications including the monitoring of IC in autoimmune diseases and the study of underlying FcγR biology.

Obinutuzumab induces superior B-cell cytotoxicity to rituximab in rheumatoid arthritis and systemic lupus erythematosus patient samples

Objective

A proportion of RA and SLE patients treated with standard doses of rituximab (RTX) display inefficient B cell deletion and poor clinical responses that can be augmented by delivering higher doses, indicating that standard-dose RTX is a sub-optimal therapy in these patients. This study aimed to investigate whether better responses could be achieved with mechanistically different anti-CD20 mAbs.

Methods

We compared RTX with obinutuzumab (OBZ), a new-generation, glycoengineered type II anti-CD20 mAb, in a series of in vitro assays measuring B cell cytotoxicity in RA and SLE patient samples.

Results

We found that OBZ was at least 2-fold more efficient than RTX at inducing B-cell cytotoxicity in in vitro whole blood assays. Dissecting this difference, we found that RTX elicited more potent complement-dependent cellular cytotoxicity than OBZ. In contrast, OBZ was more effective at evoking Fc gamma receptor-mediated effector mechanisms, including activation of NK cells and neutrophils, probably due to stronger interaction with Fc gamma receptors and the ability of OBZ to remain at the cell surface following CD20 engagement, whereas RTX became internalized. OBZ was also more efficient at inducing direct cell death. This was true for all CD19 + B cells as a whole and in naïve (IgD + CD27 - ) and switched (IgD - CD27 + ) memory B cells specifically, a higher frequency of which is associated with poor clinical response after RTX.

Conclusion

Taken together, these data provide a mechanistic basis for resistance to rituximab-induced B-cell depletion, and for considering obinutuzumab as an alternative B-cell depleting agent in RA and SLE.

B cell phenotypes in patients with rheumatoid arthritis relapsing after rituximab: expression of B cell-activating factor-binding receptors on B cell subsets

Serum levels of B cell-activating factor (BAFF) rise following rituximab (RTX) therapy in patients with rheumatoid arthritis (RA). Initiation of naive B cell return to the periphery and autoreactive B cell expansion leading to relapse after RTX may therefore be linked to interactions between BAFF and BAFF-binding receptors (BBR). Relationships between serum BAFF and BBR expression [(BAFFR, calcium signal modulating cyclophilic ligand interactor (TACI) and B cell maturation antigen (BCMA)] were determined on B cell subsets, defined using immunoglobulin (Ig)D/CD38. Twenty pre-RTX and 18 RA patients relapsing after B cell depletion were included. Results were analysed with respect to timing of relapse up to 7 months after peripheral B cell return (≥ 5 B cells/μl) and to serum BAFF levels. After B cell return, B cell populations from relapsing patients had significantly lower BAFFR⁺ expression compared to HC and pre-RTX patients. The percentage of BAFFR⁺ B cells increased with time after B cell return and was correlated inversely with serum BAFF levels. BAFFR expression remained reduced. The percentage of TACI⁺ memory B cells were lower in RA patients after RTX compared with healthy controls (HC). BCMA expression (% and expression) did not differ between patients and HC. Relapse following B cell return appeared largely independent of the percentage of BAFFR⁺ or percentage of BCMA⁺ B cells or serum BAFF levels. The lower percentage of TACI⁺ memory B cells may reduce inhibitory signalling for B cell differentiation. In patients relapsing at longer periods after B cell return, recovery of the B cell pool was more complete, suggesting that selection or expansion of autoreactive B cells may be needed to precipitate relapse.

Pragmatic Treatment of Patients With Systemic Lupus Erythematosus With Rituximab: Long-Term Effects on Serum Immunoglobulins

Objective

B cell–depletion therapy based on rituximab is a therapeutic option for refractory disease in patients with systemic lupus erythematosus (SLE). The aim of this observational study was to document long‐term effects on B cell function by following serum immunoglobulin levels in patients with SLE treated with rituximab in routine clinical practice.

Methods

We included 57 consecutive patients with SLE treated with rituximab and concomitant/sequential immunosuppressants and measured serum total IgG, IgM, and IgA and IgG anti‐dsDNA antibodies, over a median of 48 months most recent followup. Flow cytometry was used prospectively to assess B cell phenotypes in 17 of 57 patients.

Results

Twelve patients (21%) had persistent IgM hypogammaglobulinemia (<0.4 gm/liter), and 4 of 57 (5%) had low IgG (<7 gm/liter) at the most recent followup (range 12–144 months). This was not associated with serious adverse events or high anti–double‐stranded DNA (anti‐dsDNA) antibodies (>1,000 IU/ml; normal <50 IU/ml). Factors predictive of low serum IgM included baseline serum IgM ≤0.8 gm/liter (receiver operator curve analysis) and subsequent therapy with mycophenolate mofetil (MMF; odds ratio 6.8, compared with other immunosuppressants). In patients maintaining normal IgM levels (9 of 17), the frequency of circulating IgD+CD27+ B cells was significantly higher (P = 0.05). At 12 months after rituximab, 7 of 30 SLE patients with baseline anti‐dsDNA ≤1,000 IU/ml had lost seropositivity.

Conclusion

Lower baseline serum IgM levels and sequential therapy with MMF were predictive of IgM hypogammaglobulinemia after rituximab in SLE, but this was not associated with higher levels of anti‐dsDNA antibodies or an increased risk of infections. This provides useful directions for clinicians regarding rituximab and sequential immunosuppressive treatment for patients with SLE.

Characterization of B cells in healthy pregnant women from late pregnancy to post-partum: a prospective observational study

Background

B cells play a role in pregnancy due to their humoral and regulatory activities. To our knowledge, different maturational stages (from transitional to memory) of circulating B cell subsets have not yet been characterized (cell quantification and phenotype identification) in healthy pregnant women. Thus, the objective of our study was to characterize these subsets (as well as regulatory B cells) from late pregnancy to post-partum and to compare them with the circulating B cells of non-pregnant women.

Methods

In all of the enrolled women, flow cytometry was used to characterize the circulating B cell subsets according to the expression of IgD and CD38 (Bm1-Bm5 classification system). Regulatory B cells were characterized based on the expression of surface antigens (CD24, CD27, and CD38) and the production of IL-10 after lipopolysaccharide stimulation.

Results

Compared to the absolute counts of B cells in the non-pregnant women (n = 35), those in the pregnant women (n = 43) were significantly lower (p < 0.05) during the 3rd trimester of pregnancy and on delivery day (immediately after delivery). The percentages of these cells on delivery day and at post-partum were significantly lower than those in the non-pregnant women.

In general, the absolute counts and percentages of the majority of the B cell subsets were significantly lower in the 3rd trimester of pregnancy and on delivery day than in the non-pregnant women. However, these counts and percentages did not differ significantly between the post-partum and the non-pregnant women.

The most notable exceptions to the above were the percentages of naïve B cells (which were significantly higher in the 3rd trimester and on delivery day than in the non-pregnant women) and of CD24^hiCD38^hi regulatory B cells (which were significantly higher in the post-partum than in the non-pregnant women).

Conclusion

According to our study, the peripheral B cell compartment undergoes quantitative changes during normal late pregnancy and post-partum. Such findings may allow us to better understand immunomodulation during human pregnancy and provide evidence that could aid in the development of new strategies to diagnose and treat pregnancy-associated disturbances. Our findings could also be useful for studies of the mechanisms of maternal responses to vaccination and infection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-016-0927-7) contains supplementary material, which is available to authorized users.

B cell depletion with rituximab in patients with rheumatoid arthritis: Multiplex bead array reveals the kinetics of IgG and IgA antibodies to citrullinated antigens

The serology of patients with Rheumatoid arthritis (RA) is characterized by persistently raised levels of autoantibodies: Rheumatoid Factors (RhF) against Fc of IgG, and to citrullinated (Cit) protein/peptide sequences: ACPA, recognizing multiple Cit-sequences. B cell depletion therapy based on rituximab delivers good clinical responses in RA patients, particularly in the seropositive group, with responses sometimes lasting beyond the phase of B cell reconstitution. In general, ACPA levels fall following rituximab, but fluctuations with respect to predicting relapse have proved disappointing. In order to identify possible immunodominant specificities within either IgG- or IgA-ACPA we used a Multiplex bead-based array consisting of 30 Cit-peptides/proteins and 22 corresponding native sequences. The kinetics of the serum ACPA response to individual specificities was measured at key points (Baseline, B cell depletion phase, Relapse) within an initial cycle of rituximab therapy in 16 consecutive patients with severe, active RA. All had achieved significant decreases in Disease Activity Scores-28 and maintained B cell depletion in the peripheral blood (<5 CD19+cells/μl) for at least 3 months. At Baseline, mean fluorescence intensity shown by individual IgG- and IgA-ACPA were strongly correlated (R(2) = 0.75; p < 0.0001) but IgA-ACPA were approximately 10-fold lower. Data were Z-normalised in order to compare serial results and antibody classes. At Baseline, a total of 68 IgG- and 51 IgA-ACPA had Z-scores ≥ 1 (above population mean) were identified, with at least one Cit-antigen identified in each serum. ACPA to individual specificities subsequently fluctuated with 3 different patterns. Most 51/68 (75%) IgG- and 48/51 IgA-ACPA (94%) fell between Baseline and Depletion, of which 57% IgG- and 65% IgA-ACPA rebounded pre-Relapse. Interestingly, 17/68 IgG-ACPA (25%) and some IgA-ACPA (3/51; 6%) transiently increased from Baseline, subsequently falling pre-Relapse. Individual responses to particular Cit-epitopes were not linked to particular patterns of fluctuation, but IgG- and IgA-ACPA to individual Cit-antigens often followed similar courses. Some new IgG- and IgA-ACPA, generally to different Cit-antigens however, arose at Relapse in 4 patients. The complexities of the ACPA response after rituximab may therefore reflect its ability to deplete or modify the function of parent B cell clones, which varies between patients. Although relapse following rituximab invariably follows naïve B cell exit from the bone marrow, these studies show that interactions between both 'new' and residual autoreactive memory B cells may be key to resumption of symptoms. The lack of identification of any immunodominant specificity suggests that the process of citrullination, rather than any particular Cit-antigen drives the autoimmune response in RA patients.

Extended B cell phenotype in patients with myalgic encephalomyelitis/chronic fatigue syndrome: a cross-sectional study

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a heterogeneous condition of unknown aetiology characterized by multiple symptoms including fatigue, post-exertional malaise and cognitive impairment, lasting for at least 6 months. Recently, two clinical trials of B cell depletion therapy with rituximab (anti-CD20) reported convincing improvement in symptoms. A possible but undefined role for B cells has therefore been proposed. Studies of the relative percentages of B cell subsets in patients with ME/CFS have not revealed any reproducible differences from healthy controls (HC). In order to explore whether more subtle alterations in B cell subsets related to B cell differentiation exist in ME/CFS patients we used flow cytometry to immunophenotype CD19⁺ B cells. The panel utilized immunoglobulin (Ig)D, CD27 and CD38 (classical B cell subsets) together with additional markers. A total of 38 patients fulfilling Canadian, Centre for Disease Control and Fukuda ME/CFS criteria and 32 age- and sex-matched HC were included. We found no difference in percentages of classical subsets between ME/CFS patients and HC. However, we observed an increase in frequency (P < 0·01) and expression (MFI; P = 0·03) of CD24 on total B cells, confined to IgD⁺ subsets. Within memory subsets, a higher frequency of CD21⁺ CD38⁻ B cells (> 20%) was associated with the presence of ME/CFS [odds ratio: 3·47 (1·15-10·46); P = 0·03] compared with HC, and there was a negative correlation with disease duration. In conclusion, we identified possible changes in B cell phenotype in patients with ME/CFS. These may reflect altered B cell function and, if confirmed in other patient cohorts, could provide a platform for studies based on clinical course or responsiveness to rituximab therapy.

Effect of rituximab on B cell phenotype and serum B cell-activating factor levels in patients with thrombotic thrombocytopenic purpura

Autoantibodies inhibiting the activity of the metalloproteinase, ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13), underlie the pathogenesis of thrombotic thrombocytopenic purpura (TTP). Rituximab (RTX) combined with plasma-exchange (PEX) is an effective treatment in TTP. Patients can remain in remission for extended periods following PEX/RTX, and this is associated with continuing reduction in antibodies to ADAMTS13. Factors controlling B cell differentiation to autoantibody production, including stimulation through the B cell receptor and interactions with the B cell-activating factor (BAFF), may thus impact length of remission. In this cross-sectional study, we measured naive and memory B cell phenotypes [using CD19/immunoglobulin (Ig)D/CD27] following PEX/RTX treatment in TTP patients at B cell return (n=6) and in 12 patients in remission 10-68 months post-RTX. We also investigated relationships among serum BAFF, soluble CD23 (sCD23(-) a surrogate measure of acquiring B memory (CD27(+) ) phenotype) and BAFF receptor (BAFF-R) expression. At B cell return after PEX/RTX, naive B cells predominated and BAFF-R expression was reduced compared to healthy controls (P<0.001). In the remission group, despite numbers of CD19(+) B cells within normal limits in most patients, the percentage and absolute numbers of pre-switch and memory B cells remained low, with sCD23 levels at the lower end of the normal range. BAFF levels were correlated inversely with BAFF-R expression and time after therapy. In conclusion, the long-term effects of RTX therapy in patients with TTP included slow regeneration of memory B cell subsets and persistently reduced BAFF-R expression across all B cell subpopulations. This may reflect the delay in selection and differentiation of potentially autoreactive (ADAMTS13-specific) B cells, resulting in relatively long periods of low disease activity after therapy.

Expression of the inherently autoreactive idiotope 9G4 on autoantibodies to citrullinated peptides and on rheumatoid factors in patients with early and established rheumatoid arthritis

BACKGROUND

The pre-symptomatic stage of Rheumatoid arthritis (RA) is associated with pro-inflammatory cytokines and autoantibodies. High levels and epitope spread by Rheumatoid factors (RhF) and autoantibodies to citrullinated proteins signify progression towards disease expression. In established RA, the persistence of high autoantibody levels reflects production by both long-lived plasma cells and short-lived plasmablasts. Neither the relative contributions to pathogenesis by autoantibodies from either source, nor the factors responsible for deciding the fate of autoantigen specific 'parent' B-cells, is understood. Phenotypic markers identifying subsets of autoreactive B-cells are therefore of interest in understanding the origin and perpetuation of the autoimmune response in RA. One such phenotypic marker is the rat monoclonal antibody, 9G4, which recognises an idiotope on immunoglobuins derived from the inherently autoreactive VH-gene, VH4-34. We therefore investigated whether the 9G4 idiotope was expressed on autoantibodies in patients with RA.

METHODOLOGY/PRINCIPAL FINDINGS

Sera from 19 patients with established RA and those with <1year history of untreated polyarthritis either resolving into RA (n = 42) or non-RA diagnosis (n = 31) were included. Autoantibodies to cyclic citrullinated peptides (CCP), RhF and co-expression of the 9G4 idiotope were measured by ELISA. 9G4 recognised a population of anti-CCP antibodies in the majority of sera from patients with established disease and also in samples from patients with early disaese. 9G4+RhF levels were generally lower and not associated with positivity for, or levels of 9G4+CCP.

CONCLUSIONS/SIGNIFICANCE

The persistence of 9G4+ immunoglobulins, of any isotype, in serum is rare. We describe here the novel finding of 9G4 expression on anti-CCP antibodies in patients from the earliest symptoms of RA through to established disease. Our results suggest that 9G4 expression on anti-CCP autoantibodies was not due to polyclonal expansion of VH4-34-encoded immunoglobulins. These studies may therefore provide a new focus for investigation into the evolution of the autoimmune response in RA patients.

Effects of rituximab-based B-cell depletion therapy on skin manifestations of lupus erythematosus--report of 17 cases and review of the literature

Cutaneous manifestations occur frequently in systemic lupus erythematosus (SLE) and are pathognomonic in subacute-cutaneous lupus erythematosus (SCLE) and chronic cutaneous lupus erythematosus (CCLE). Although B-cell depletion therapy (BCDT) has demonstrated efficacy in SLE with visceral involvement, its usefulness for patients with predominant skin manifestations has not been fully established. In this single-centre, retrospective study 14 consecutive SLE, one CCLE and two SCLE patients with recalcitrant skin involvement were treated with 2 × rituximab 1 g, and 1 × cyclophosphamide 750 mg.

Six months after BCDT, nine of 17 (53%) patients were in complete (CR) or partial remission (PR). Relapses occurred in 12 patients (71%) at a mean time of 10 ± 1.8 months after BCDT. A second cycle of BCDT achieved a more sustained remission in seven of nine patients (78%) lasting for a mean time of 18.4 ± 2.7 months. Minor adverse events were experienced by three patients. Mean follow-up was 30 months.

Our own results and the literature review demonstrate that BCDT based on rituximab is well tolerated and may be effective for cutaneous lesions of lupus erythematosus. Randomized controlled trials are necessary to further evaluate the value of BCDT for this group of patients.

B-cell subpopulations in humans and their differential susceptibility to depletion with anti-CD20 monoclonal antibodies

In humans, different B-cell subpopulations can be distinguished in peripheral blood and other tissues on the basis of differential expression of various surface markers. These different subsets correspond to different stages of maturation, activation and differentiation. B-cell depletion therapy based on rituximab, an anti-CD20 mAb, is widely used in the treatment of various malignant and autoimmune diseases. Rituximab induces a very significant depletion of B-cell subpopulations in the peripheral blood usually for a period of 6 to 9 months after one cycle of therapy. Cells detected circulating during depletion are mainly CD20 negative plasmablasts. Data on depletion of CD20-expressing B cells in solid tissues are limited but show that depletion is significant but not complete, with bone marrow and spleen being more easily depleted than lymph nodes. Factors influencing depletion are thought to include not only the total drug dose administered and distribution into various tissues, but also B-cell intrinsic and microenvironment factors influencing recruitment of effector mechanisms and antigen and effector modulation. Available studies show that the degree of depletion varies between individuals, even if treated with the same dose, but that it tends to be consistent in the same individual. This suggests that individual factors are important in determining the final extent of depletion.

Baseline serum immunoglobulin levels in patients with rheumatoid arthritis: relationships with clinical parameters and with B-cell dynamics following rituximab

OBJECTIVES

To investigate whether levels of serum immunoglobulins (sIgs) at baseline were associated with clinical parameters or B-cell dynamics following rituximab (RTX) in patients with rheumatoid arthritis (RA).

METHODS

Baseline Ig levels, C-reactive protein (CRP), DAS28 and CD19+ve B-cell count (baseline, 1, 3 and 5 months) in 112 patients with RA after 1 cycle of RTX were included. All showed adequate B-cell depletion (<5 CD19+B cells/μl) after 1 month. Normal sIg ranges were for IgA (0.7-4.0 g/L), IgG (7.0-16.0 g/L), and IgM (0.4-2.3 g/L).

RESULTS

Baseline IgA levels were raised in 29 patients, IgG in 18 and IgM in 11. CRP levels were significantly higher in patients with raised IgA and IgG compared to patients with normal levels (p=0.0002; p=0.03). At nadir after RTX, median levels of all sIgs decreased significantly although 16 patients (55%) remained with raised IgA, 28% IgG (5/18) and 27% IgM (3/11). Patients with raised IgA had higher minimum levels reached of CRP and of DAS28 (p=0.002; p=05). After 5 months, a higher percentage of patients with raised baseline sIgA had repopulated and were found to have shorter clinical responses than those with sIgs within normal limits.

CONCLUSIONS

sIgA levels in RA patients remained raised in a higher proportion of patients than other sIg after RTX. Raised sIgA was associated with a less robust clinical response to RTX and with B-cell repopulation coincident with relapse. Expanded or more permissive microenvironments for long-lived IgA plasma cells may be related to the presence of disease more refractive to B-cell depletion therapy.

Biologic therapy and pregnancy. A systematic literature review

AIM

To review available data regarding the safety of biological therapies during pregnancy, focusing on agents used in rheumatology.

METHODS

A systematic literature search was carried out to identify all studies with human data on fetal and/or child outcomes following exposure to biologic agents during pregnancy.

RESULTS

A total of 65 publications out of 745 identified references were included in the review.

CONCLUSIONS

Experience with pregnancy exposure to anti-TNF agents has been slowly accumulating. Although the numbers are small and with few controlled studies the reviewed data suggest that the overall risk of TNF antagonists is relatively low and benefits may outweigh the risks of drug exposure to the fetus. Information on other biologic agents is still very limited. Large controlled studies with longer follow-up periods will be necessary before firm conclusions about the safety of biologics du-ring conception and pregnancy can be drawn.

B-cell-activating factor receptor expression on naive and memory B cells: relationship with relapse in patients with rheumatoid arthritis following B-cell depletion therapy

Objectives

To examine the expression of B-cell-activating factor receptor (BAFF-R) on naive CD27− and memory CD27+ B cells in normal individuals and patients with rheumatoid arthritis (RA) undergoing B-cell depletion therapy with rituximab.

Patients and Methods

BAFF-R expression on B-cell subsets was determined in normal controls (NC; n=11), active patients with RA pre-rituximab (pre-RX; n=15), relapsing patients either concordant for B-cell repopulation (C-R, n=13) or discordant, with relapse more than 3 months after repopulation (D-R, n=11) and patients in remission over 3 months postrepopulation (discordant non-relapsing (D-NR), n=5). Serum BAFF was measured by ELISA and analysed using Mann–Whitney.

Results

There was no significant difference between NC, pre-RX and D-NR patients in %BAFF-R-positive B cells or mean fluorescence intensity (MFI) in naive and memory B cells. Relapsing patients had significantly lower MFI and %BAFF-R-positive cells in both naive and memory compartments from NC and pre-RX (C-R and D-R; p<0.01). BAFF levels in pre-RX patients were within the normal range and did not correlate with BAFF-R expression in any patient group. D-NR patients had relatively lower proportions of pre and postswitch CD27+ B cells than pre-RX patients (D-NR vs pre-RX; p<0.05 for both) and also lower numbers of postswitch B cells than D-R patients (D-NR vs D-R, p<0.05).

Conclusion

BAFF-R expression was significantly reduced on both naive and memory B cells in patients at relapse, regardless of the relationship with B-cell repopulation or serum BAFF levels. Re-establishment of active disease was also associated with an increase in class-switch recombination. Factors responsible for lower levels of BAFF-R may relate to altered thresholds for autoreactive B-cell generation at relapse in patients with RA.

Anti-tumour necrosis factor therapy and B cells in rheumatoid arthritis

The efficacy of B-cell depletion therapy in rheumatoid arthritis (RA) has led to a renewed interest in B cells and their products and the role they play in the pathogenesis of the disease. Agents blocking tumour necrosis factor (TNF) are also very effective in the treatment of RA. It has long been known that the use of anti-TNF therapy can be associated with development of anti-nuclear and anti-double-stranded DNA antibodies and, more rarely, a lupus-like syndrome. Recently, studies have been published investigating further possible effects of anti-TNF agents on B cells and whether these could contribute to their effectiveness in RA.

Translational Mini-Review Series on B Cell-Directed Therapies: The pathogenic role of B cells in autoantibody-associated autoimmune diseases--lessons from B cell-depletion therapy

B cell depletion therapy with rituximab (BCDT) is a licensed treatment for rheumatoid arthritis and has shown promising results in the treatment of severe, refractory patients with other autoantibody-associated autoimmune diseases (AAID). The exact role that B cells play in the pathogenesis of AAID and consequently the mechanisms by which BCDT is effective are not known. The two more widely discussed hypotheses are that BCDT is effective because it removes the precursors of plasma cells producing pathogenic autoantibody species, or because it depletes a critical mass of autoreactive B cell clones that present antigen to pathogenic autoreactive T cells. This review will focus on the effects of BCDT and whether the response of patients with AAID to BCDT could be due ultimately to its effects on autoantibodies. A better knowledge of the main role that B cells play in the pathogenesis of the different diseases and a better understanding of the most likely mechanism of relapse following an earlier response to BCDT would help to guide further developments of B cell targeting therapies and potentially increase the chance of designing a protocol that could induce a long-term remission.

A retrospective seven-year analysis of the use of B cell depletion therapy in systemic lupus erythematosus at University College London Hospital: the first fifty patients

OBJECTIVE

To describe the 6-month clinical outcome and the long-term safety profile of B cell depletion therapy (BCDT) in 50 patients with active systemic lupus erythematosus (SLE), who were nonresponsive or poorly responsive to conventional immunosuppression.

METHODS

All except 4 of 50 patients with active SLE received 1 gm of rituximab, 750 mg of cyclophosphamide, and 100-250 mg of methylprednisolone, administered on 2 occasions 2 weeks apart, to achieve B cell depletion. Clinical outcome was assessed using the British Isles Lupus Assessment Group (BILAG) activity index and serial serologic measurements of disease activity. Remission was defined as a change from a BILAG A or B score to a C or D score in every organ system. Partial remission was a change from a BILAG A or B score to a C or D score in at least 1 system, but with the persistence of 1 score of A or B in another system. No improvement was defined as a BILAG A or B score that remained unchanged after treatment.

RESULTS

Of the 45 patients available for followup at 6 months, 19 patients (42%) achieved remission, and 21 patients (47%) reached partial remission after 1 cycle of BCDT (mean followup 39.6 months). BCDT resulted in a decrease in median global BILAG scores from 12 to 5 (P < 0.0001) and median anti-double-stranded DNA antibody titers from 106 to 42 IU/ml (P < 0.0001), and an increase in the median C3 level from 0.81 to 0.95 mg/liter (P < 0.02) at 6 months. Five serious adverse events were observed.

CONCLUSION

BCDT is an effective treatment for patients with active SLE whose disease has failed to respond to standard immunosuppressive therapy. Although the safety profile of BCDT is favorable, ongoing monitoring is required.

B cell depletion therapy for patients with systemic lupus erythaematosus results in a significant drop in anticardiolipin antibody titres

BACKGROUND

B cell depletion therapy (BCDT) has recently been used with success to treat patients with rheumatoid arthritis and systemic lupus erythematosus (SLE). As antiphospholipid antibodies have been implicated in the pathogenesis of the antiphospholipid syndrome (APS), we asked the question whether BCDT affects levels of IgG anticardiolipin antibodies (aCL) in our cohort of 32 SLE patients given this treatment.

METHODS

We identified seven SLE patients who had undergone BCDT and had had at least two moderate positive aCL titres at least 12 weeks apart. Of these only one patient had APS. IgG aCL were measured at time 0 and 6-9 months post BCDT.

RESULTS

At time 0, the mean IgG aCL level was 20.6 standardized IgG antiphospholipid units (GPLU) (range (SD) 10-32, (10.1), normal level <5). At 6-9 months post depletion the IgG aCL levels in six of the seven patients was undetectable and in the other patient the level reduced from 25 GPLU to 15 GPLU (p<0.005, two-tailed paired t test). At baseline, only one patient had a mildly positive anti-beta(2)-glycoprotein I (beta(2)GPI) antibody level at 30% (compared to an in-house standard), which fell to 5% post-BCDT.

CONCLUSIONS

This small observational study in patients with SLE is the first to demonstrate that BCDT results in a significant reduction in levels of IgG aCL.

B cell depletion therapy in systemic lupus erythematosus: relationships among serum B lymphocyte stimulator levels, autoantibody profile and clinical response

OBJECTIVE

To assess the relationships between serum B lymphocyte stimulator (BLyS) levels, autoantibody profile and clinical response in patients with systemic lupus erythematosus (SLE) following rituximab-based B cell depletion therapy (BCDT).

METHODS

A total of 25 patients with active refractory SLE were followed for >or=1 year following BCDT. Disease activity was assessed using the British Isles Lupus Assessment Group (BILAG) system, and serum levels of BLyS and autoantibodies to dsDNA and extractable nuclear antigens (ENA) measured by ELISA. Serum immunoglobulins and anti-dsDNA antibodies were assessed for expression of the 9G4 idiotope (indicating VH4-34 germline gene origin).

RESULTS

Following BCDT, all patients depleted in the peripheral blood and improved clinically for >or=3 months. Pre-BCDT BLyS levels were quantifiable (median 1.9 ng/ml) in 18/25 patients and rose in most patients at 3 months post-BCDT (median 4.15 ng/ml). Nine patients, all with quantifiable pre-BCDT serum BLyS, experienced a disease flare within 1 year. This group of patients was more likely to harbour anti-Ro/SSA antibodies (odds ratio 1.76; p = 0.06) with higher serum levels (p = 0.0027; Mann-Whitney U test). Serum levels of anti-ribonucleoprotein (RNP)/Sm were also higher in this group (p<0.05). Expression of VH4-34 by serum immunoglobulins and anti-dsDNA antibodies had no predictive value for the length of clinical response.

CONCLUSIONS

Patients with SLE with an expanded autoantibody profile and raised BLyS levels at baseline had shorter clinical responses to BCDT. This may reflect a greater propensity to, and degree of, epitope spreading in such patients and suggests that treatment regimens beyond BCDT may be necessary to induce long-lasting clinical remissions in these individuals.

B cell depletion therapy in systemic lupus erythematosus: long-term follow-up and predictors of response

OBJECTIVES

To describe the long-term clinical outcome and safety profile of B cell depletion therapy (BCDT) in patients with systemic lupus erythematosus (SLE). It was also determined whether baseline parameters can predict the likelihood of disease flare.

METHODS

32 patients with refractory SLE were treated with BCDT using a combination protocol (rituximab and cyclo-phosphamide). Patients were assessed with the British Isles Lupus Assessment Group (BILAG) activity index, and baseline serology was measured. Flare was defined as a new BILAG 'A' or two new subsequent 'B's in any organ system.

RESULTS

Of the 32 patients, 12 have remained well after one cycle of BCDT (median follow-up 39 months). BCDT was followed by a decrease of median global BILAG scores from 13 to 5 at 6 months (p = 0.006). Baseline anti-extractable nuclear antigen (ENA) was the only identified independent predictor of flare post-BCDT (p = 0.034, odds ratio = 8, 95% CI 1.2 to 55) from multivariable analysis. Patients with low baseline serum C3 had a shorter time to flare post-BCDT (p = 0.008). Four serious adverse events were observed.

CONCLUSION

Autoantibody profiling may help identify patients who will have a more sustained response. Although the long-term safety profile of BCDT is favourable, ongoing vigilance is recommended.

B cell depletion therapy in rheumatic disease

B cell depletion therapy was introduced for auto-antibody associated rheumatic disease in 1998. Encouraging pilot studies in rheumatoid arthritis were followed by randomised controlled trials confirming major benefit. Licensing for use in patients unable to benefit from tumour necrosis factor alpha (TNFalpha) neutralising agents is envisaged shortly. Open studies in other disorders, in particular systemic lupus erythematosus (SLE), have also suggested benefit and its use in life-threatening situations is becoming widespread. Toxicity appears to compare favourably with other agents, but respiratory problems may be more common. Repeated therapy is effective, but may lead to hypogammaglobulinemia. Rituximab is currently the main agent used but other agents are in development. Optimal protocols are not well characterised and will probably be different for different conditions.

Repeated B lymphocyte depletion with rituximab in rheumatoid arthritis over 7 yrs

OBJECTIVE

To assess safety and efficacy of repeated B-cell depletion with rituximab in patients with rheumatoid arthritis (RA).

METHODS

Thirty-seven patients with refractory RA entered into a programme of repeated B-lymphocyte depletion (up to 5 cycles, 89 cycles in total) with protocols based on the anti-CD20 monoclonal antibody, rituximab, have been observed over periods of >5 yrs (n = 22) or 3-5 yrs (n = 14).

RESULTS

Twenty two subjects have been followed up for >5 yrs. Average duration of benefit per cycle was 15 months (maximum 43 months), and time to re-treatment 20 months. Nineteen patients remain on the programme. Patients were withdrawn for lack of efficacy (n = 5), hypersensitivity infusion reaction (n = 1), brevity of response (n = 8), or occurrence of adverse respiratory events (n = 1). Sixteen major lower respiratory events occurred during the 180 patient-yrs of follow-up. Of these only one had low IgG. In patients receiving rituximab +/- cyclophosphamide (cy) carcinomata have developed as follows: breast (3, +cy), ovary (1, +cy), transitional cell (1, +cy), and renal cell (1, -cy). Falls in total immunoglobulin levels to below the normal range occurred in 12 patients for IgM (undetectable levels in three after repeated cycles), seven for IgG and one for IgA, not taking into account patients who started off with low immunoglobulin levels before the first cycle.

CONCLUSION

Repeated B-lymphocyte depletion over a 5-yr period appears to be an acceptable and relatively well-tolerated therapy in RA with a relatively high rate of continuation. Long-term effects on immunoglobulin levels require surveillance.

Bone marrow B-lineage cells in patients with rheumatoid arthritis following rituximab therapy

OBJECTIVE

To assess the presence and phenotype of B-lineage cells in the bone marrow (BM) of rheumatoid arthritis (RA) patients after rituximab therapy.

METHODS

Six patients were studied. BM aspirates were collected 3 months after the treatment and analysed using the four-colour flow cytometry.

RESULTS

CD19+ (B-lineage) cells in BM samples varied from 0.1 to 3.25% in the lymphoid gate. CD34+ cells varied from 1.23 to 4.86%. The proportion of CD34+ cells committed to the B-lineage varied between 0 and 42.19%. Pro-B-cells were undetectable in one case. The majority of B-cell precursors were pro-B-cells in Patients 5 and 6 (50 and 62% of CD19+ cells, respectively), pre-B-cells in Patients 3 and 4 (64 and 70%) and immature B-cells in Patient 1 (44%). Detectable CD20 expression on CD19+ cells was either low or absent. Plasma cells varied from 0.01 to 0.36% of the total nucleated cells. There was a trend towards longer duration of clinical response in patients with evidence of more complete depletion in BM.

CONCLUSION

In this small cohort of RA patients treated with rituximab, differences in proportion and phenotype of CD19+ BM cells were detected. These differences suggest variation in the degree of depletion achieved and correlate with time to relapse. Although pro-B-cells are not targeted directly by rituximab as they do not express CD20, the levels were unexpectedly low.

Circulating levels of B lymphocyte stimulator in patients with rheumatoid arthritis following rituximab treatment: relationships with B cell depletion, circulating antibodies, and clinical relapse

OBJECTIVE

To assess the effects of B lymphocyte depletion on serum B lymphocyte stimulator (BLyS; trademark of Human Genome Sciences, Rockville, MD) levels in patients with rheumatoid arthritis (RA), and to assess the relationship of serum BLyS levels with peripheral blood B cell depletion, levels of autoantibodies and antimicrobial antibodies, the return of peripheral blood B cells, and clinical relapse.

METHODS

Fifteen patients with active RA underwent rituximab-based B cell depletion therapy (BCDT). Disease activity was assessed clinically, peripheral blood CD19+ B cell counts were determined by flow cytometry, and serum levels of BLyS, IgM, IgA, and IgG rheumatoid factors (RFs), anti-cyclic citrullinated peptide, and antimicrobial antibodies were assessed using enzyme-linked immunosorbent assays.

RESULTS

Peripheral blood B cell depletion was achieved in all 15 patients, and an American College of Rheumatology 20% response was achieved in 13 patients. Following clinical relapse, 7 patients underwent at least 1 additional cycle of BCDT. In every case, serum BLyS levels markedly rose post-BCDT and remained elevated for at least 1-2 months. Serum levels of RF, but not those of anti-tetanus toxoid or anti-pneumococcal polysaccharide antibodies, fell significantly. A decline in serum BLyS levels was associated with the reemergence of B cells in peripheral blood, which, in turn, antedated clinical relapse by variable periods of time. The patterns of B cell depletion, serum BLyS and antibody levels, and clinical relapse for each BCDT cycle were remarkably similar in re-treated patients.

CONCLUSION

Rituximab-based BCDT leads to marked increases in serum BLyS levels. This may contribute significantly to the survival and/or regeneration of B cell populations capable of triggering clinical relapse.

B cell depletion therapy in systemic lupus erythematosus: Effect on autoantibody and antimicrobial antibody profiles

OBJECTIVE

Autoantibody production in patients with systemic lupus erythematosus (SLE) is associated with abnormalities of B cell function and phenotype. Clinical responses to B cell depletion therapy (BCDT), based on rituximab, are encouraging. Therefore, we undertook this study to investigate the effect of BCDT on antibody profiles.

METHODS

Serial sera from 16 patients with active, refractory SLE were assayed for antinucleosome antibodies, anti-double-stranded DNA (anti-dsDNA), anti-extractable nuclear antigen, anti-tetanus toxoid, and antibodies to pneumococcal capsular polysaccharide for at least 1 year following BCDT. Anti-dsDNA antibodies derived from the V(H)4.34 immunoglobulin germ line gene (9G4+) were also measured.

RESULTS

All patients achieved peripheral B cell depletion and improved clinically for at least 3 months. Antinucleosome and anti-dsDNA antibodies decreased to a mean +/- SD of 64 +/- 37% and 38 +/- 33% of baseline values, respectively, by 6-8 months post-BCDT. Levels of other autoantibodies and antimicrobial antibodies were generally unchanged. In the 9 of 16 patients who were still well at 1 year, anti-dsDNA antibodies fell to 42 +/- 36% of baseline values at 6-8 months and to 37 +/- 33% at 10-14 months. In patients who had disease flares within 1 year of BCDT, levels of these antibodies decreased to 60 +/- 40% and 83 +/- 93% of baseline values at 6-8 months and at 10-14 months, respectively. Circulating anti-dsDNA antibodies were positive for 9G4 expression in 4 of 6 patients tested, and flares in 2 of these patients were accompanied by rises in 9G4+ anti-dsDNA antibodies.

CONCLUSION

These observations suggest that B cell clones committed to producing antinucleosome and anti-dsDNA antibodies, including the V(H)4.34 subpopulation of anti-dsDNA antibodies, have a relatively rapid turnover compared with B cell clones producing other antibodies. There was also a trend toward a greater and more sustained decrease in anti-dsDNA antibodies in patients with clinical benefit lasting >1 year.

Reconstitution of peripheral blood B cells after depletion with rituximab in patients with rheumatoid arthritis

OBJECTIVE

To study the quantitative and phenotypic reconstitution of peripheral blood B cells and its relationship to the dynamics of clinical response in patients with rheumatoid arthritis (RA) following B cell depletion with rituximab.

METHODS

Twenty-four patients with active RA treated with rituximab were studied. Flow cytometry with combinations of monoclonal antibodies to B cell and T cell subsets was used.

RESULTS

The frequency and total number of CD19+ cells in the peripheral blood decreased a mean of 97% for more than 3 months in all but 1 patient following rituximab therapy. All B cell populations were depleted. More than 80% of residual B cells showed a memory or plasma cell precursor phenotype. B cell repopulation occurred a mean of 8 months after treatment and was dependent on the formation of naive B cells, which showed an increased expression of CD38 and CD5. During repopulation, increased numbers of circulating immature B cells, CD19+,IgD+,CD38(high),CD10(low),CD24(high) cells, were identified. Patients who experienced a relapse of RA on return of B cells tended to show repopulation with higher numbers of memory B cells. A small number of T cells and natural killer cells expressed low levels of CD20. These cells were depleted following rituximab therapy and returned to the circulation a mean of 5 months after treatment. No other significant changes were detected in the T cell populations studied.

CONCLUSION

Rituximab induced a profound depletion of all peripheral blood B cell populations in patients with RA. Repopulation occurred mainly with naive mature and immature B cells. Patients whose RA relapsed on return of B cells tended to show repopulation with higher numbers of memory B cells.

Repeated B cell depletion in treatment of refractory systemic lupus erythematosus

OBJECTIVES

To report the clinical outcome and safety profile of repeated B cell depletion in seven patients with refractory systemic lupus erythematosus (SLE).

METHODS

Since June 2000, seven patients with refractory SLE had repeated cycles of B cell depletion (18 cycles in total, up to three cycles per patient) because of disease relapse. The clinical response (assessed by the British Isles Lupus Activity Guide (BILAG) activity index), duration of B cell depletion, and adverse events in these patients was reviewed.

RESULTS

Four patients (Nos 1, 2, 3, 6) had three cycles of treatment and three (Nos 4, 5, 7) had two cycles. Four of the seven patients (Nos 1, 3, 5, 6) improved. The mean global BILAG scores dropped from 15 to 6 at 5-7 months. The median duration of clinical response and B cell depletion was 13 months and 6 months, respectively. After the third cycle, 2/4 patients (Nos 1 and 2) improved. The median duration of clinical benefit was 12 months. Most patients tolerate re-treatment very well.

CONCLUSION

Re-treatment with B cell depletion of patients with severe SLE is safe and may be effective for 6-12 months on average.

B-cell depletion in the treatment of patients with systemic lupus erythematosus: a longitudinal analysis of 24 patients

OBJECTIVES

To assess the clinical and basic serological consequences of B-cell depletion with rituximab in the treatment of patients with systemic lupus erythematosus (SLE) who have failed conventional immunosuppression.

METHODS

An open study of 24 patients with severe SLE followed for a minimum of 3 months is reported. In the majority of patients (19 out of 24), 6 months follow-up data are described. Disease activity in these patients was assessed every 1-2 months using the British Isles Lupus Assessment Group (BILAG) system and estimates of anti-double-stranded DNA antibodies and serum C3 levels. During the follow-up period, significant side-effects were sought and the reduction in oral prednisolone was recorded. It was our general practice to stop concomitant immunosuppression (e.g. azathioprine, mycophenolate) when B-cell depletion was given (in most cases in the form of two 1 g intravenous infusions of rituximab 2 weeks apart accompanied by two 750 mg intravenous cyclophosphamide infusions and two methylprednisolone infusions of 250 mg each).

RESULTS

Twenty-two patients were female and two male. At the time of B-cell depletion, the mean age was 28.9 yr (range 17-49) and the mean disease duration was 7.9 yr (range 1-18). The global BILAG score (P < 0.00001), serum C3 (P < 0.0005) and double-stranded DNA binding (P < 0.002) all improved from the time of B-cell depletion to 6 months after this treatment. Only one patient failed to achieve B-lymphocyte depletion in the peripheral blood. The period of B-lymphocyte depletion ranged from 3 to 8 months except for one patient who remains depleted at more than 4 yr. Analysis of the regular BILAG assessments showed that improvements occurred in each of the eight organs or systems. The mean daily prednisolone dose fell from 13.8 mg (s.d. 11.3) to 10 mg (s.d. 3.1).

CONCLUSION

In this open study of patients who had failed conventional immunosuppressive therapy, considerable utility in the use of B-cell depletion has been demonstrated. Our data provide strong support for the performance of a full double-blind control trial.