Decreased Serum IgM Research Articles

Povetacicept, an Enhanced Dual APRIL/BAFF Antagonist That Modulates B Lymphocytes and Pathogenic Autoantibodies for the Treatment of Lupus and Other B Cell-Related Autoimmune Diseases.

Dysregulated APRIL/BAFF signaling is implicated in the pathogenesis of multiple autoimmune diseases, including systemic lupus erythematosus and lupus nephritis. We undertook this study to develop and evaluate a high-affinity APRIL/BAFF antagonist to overcome the clinical limitations of existing B cell inhibitors. A variant of TACI-Fc generated by directed evolution showed enhanced binding for both APRIL and BAFF and was designated povetacicept (ALPN-303). Povetacicept was compared to wild-type (WT) TACI-Fc and related molecules in vitro and in vivo. Povetacicept inhibited APRIL and BAFF more effectively than all evaluated forms of WT TACI-Fc and selective APRIL and BAFF inhibitors in cell-based reporter assays and primary human B cell assays, mediating potent suppression of B cell proliferation, differentiation, and immunoglobulin (Ig) secretion. In mouse immunization models, povetacicept significantly reduced serum immunoglobulin titers and antibody-secreting cells more effectively than anti-CD20 monoclonal antibodies, WT TACI-Fc, or APRIL and BAFF inhibitors. In the NZB × NZW mouse lupus nephritis model, povetacicept significantly enhanced survival and suppressed proteinuria, anti-double-stranded DNA antibody titers, blood urea nitrogen, glomerulonephritis, and renal immunoglobulin deposition. In the bm12 mouse lupus model, povetacicept significantly reduced splenic plasmablasts, follicular helper T cells, and germinal center B cells. In non-human primates, povetacicept was well tolerated, exhibited high serum exposure, and significantly decreased serum IgM, IgA, and IgG levels after a single dose. Enhanced APRIL and BAFF inhibition by povetacicept led to greater inhibition of B cell populations critical for autoantibody production compared to WT TACI-Fc and CD20-, APRIL-, or BAFF-selective inhibitors. Potent, dual inhibition by povetacicept has the potential to significantly improve clinical outcomes in autoantibody-related autoimmune diseases.

IgM Deficiency in Autoimmune Blistering Mucocutaneous Diseases Following Various Treatments: Long Term Follow-Up and Relevant Observations.

IgM deficiency has been reported in patients with many autoimmune diseases treated with Rituximab (RTX). It has not been studied, in detail, in autoimmune mucocutaneous blistering diseases (AIMBD). Our objectives were: (i) Examine the dynamics of IgM levels in patients with and without RTX. (ii) Influence of reduced serum IgM levels on clinical and laboratory parameters. (iii) Explore the possible molecular and cellular basis for reduced serum IgM levels. This retrospective study that was conducted in a single-center from 2000 to 2020. Serial IgM levels were studied in 348 patients with five AIMBD (pemphigus vulgaris, pemphigus foliaceus, bullous pemphigoid, mucous membrane pemphigoid, and ocular cicatricial pemphigoid) and found decreased in 55 patients treated with RTX, IVIG, and conventional immunosuppressive therapy (CIST). Hence the incidence of decreased serum IgM is low. The incidence of decreased IgM in patients treated with RTX was 19.6%, in patients treated with IVIG and CIST, it was 52.8% amongst the 55 patients. IgM levels in the post-RTX group were statistically significantly different from the IVIG group (p<0.018) and CIST group (p<0.001). There were no statistically significant differences between the groups in other clinical and laboratory measures. Decreased serum IgM did not affect depletion or repopulation of CD19+ B cells. Patients in the three groups achieved clinical and serological remission, in spite of decreased IgM levels. Decrease in IgM was isolated, since IgG and IgA were normal throughout the study period. Decreased IgM persisted at the same level, while the patients were in clinical remission, for several years. In spite of persistent decreased IgM levels, the patients did not develop infections, tumors, other autoimmune diseases, or warrant hospitalization. Studies on IgM deficiency in knockout mice provided valuable insights. There is no universally accepted mechanism that defines decreased IgM levels in AIMBD. The data is complex, multifactorial, sometimes contradictory, and not well understood. Nonetheless, data in this study provides novel information that enhances our understanding of the biology of IgM in health and disease.

Challenges in investigating patients with isolated decreased serum IgM: The SIMcal study.

The clinical consequences of isolated decreased serum immunoglobulin (Ig)M are not sufficiently known. Therefore, it is difficult to determine the clinical policy following such a finding. Only few reported IgM‐deficient patients fulfil the European Society for Immunodeficiencies (ESID) diagnostic criteria for selective IgM deficiency (true sIgMdef), or their diagnosis is uncertain due to insufficient laboratory data (possible sIgMdef). Decreased serum IgM is often incidentally found in asymptomatic adults. The objective of our study was to further characterize true sIgMdef and to compare the European data collected through the ESID Registry community (tertiary centres) to our previously published Dutch cohort (secondary centre). Fifteen centres (12 countries) participated with 98 patients. Patients were excluded if serum IgM was only determined once (n = 14), had normalized (n = 8), or if they also had other immunological abnormalities (n = 15). Ten patients (5 adults) completely fulfilled the ESID criteria for true sIgMdef. Age‐matched cut‐off values varied widely between centres; when using the ESID diagnostic protocol reference values, only six patients (five adults) had true sIgMdef. Because of these small numbers, further analyses were performed in patients with true or possible sIgMdef (13 adults, 48 children). Respiratory infections were commonly reported at presentation (adults 54%, children 60%). Symptomatic adults had lower serum IgM levels (mean 0.27 g/L, 95% CI 0.22‐0.31) than those without symptoms (mean 0.33 g/L, 95% CI 0.30‐0.36; P = 0.02). To be able to explore the clinical consequences of true sIgMdef, we should fully analyse and accurately describe those patients in whom a decreased serum IgM is found.

Dietary administration of β-1,3/1,6-glucan and probiotic strain Shewanella putrefaciens, single or combined, on gilthead seabream growth, immune responses and gene expression

It is widely known that β-glucans and probiotic bacteria are good immunostimulants for fish. In the present work we have evaluated the dietary effect of β-1,3/1,6-glucan (isolated from Laminarina digitata) and Pdp 11 (Shewanella putrefaciens, probiotic isolated from gilthead seabream skin), single or combined, on growth, humoural (seric level of total IgM antibodies and peroxidase and antiprotease activities) and cellular innate immune response (peroxidase and phagocytic activities of head-kidney leucocytes), as well as the expression of immune-related genes in gilthead seabream (Sparus aurata). Four treatment groups were established: control (non-supplemented diet), Pdp 11 (109 cfu g−1), β-1,3/1,6-glucan (0.1%) and β-1,3/1,6-glucan + Pdp 11 (0.1% and 109 cfu g−1, respectively). Fish were sampled after 1, 2 and 4 weeks of feeding. Interestingly, all supplemented diets produced increments in the seabream growth rates, mainly the Pdp 11-suplemented diet. Overall, Pdp 11 dietary administration resulted in decreased serum IgM levels and peroxidase activity. However, the seric antiprotease activity was increased in fish fed with both supplements together. Furthermore, β-1,3/1,6-glucan and combined diet increased phagocytic activity after 2 or 4 weeks. At gene level, IL-1β and INFγ transcripts were always up-regulated in HK but only the interleukin reached significance after 4 weeks in the group fed with β-glucan. On the contrary, IgM gene expression tended to be down-regulated being significant after 1 week in seabream specimens fed with β-glucan or β-glucan plus Pdp 11. These results suggest that β-1,3/1,6-glucan and Pdp 11 modulate the immune response and stimulates growth of the gilthead seabream, one of the species with the highest rate of production in Mediterranean aquaculture.

A Shorter Time to First Treatment and Worst Overall survival Is Observed in Cll Patients with Reduced Serum IgM As Evaluated with Novel Serum Immunoassays

AbstractAbstract 4585 Background and Aims:Reduced serum IgM levels were proposed as an unfavorable prognostic factor in multiple myeloma1. We therefore investigated the possible impact of decreased serum IgM concentrations on the outcome of Chronic Lymphocytic Leukemia (CLL) patients, a disease that is frequently characterized by severe hypogammaglobulinemia. Serum IgM levels were measured by 2 methods. Patients and methods:188 patients with CLL were studied. Of them 54%, 27%,10%, 7% και 2% where in RAI stage 0, 1, 2, 3, 4 respectively while 65%, 22% and 13% in Binet stages A, B and C. IgM was determined at diagnosis by both classical nephelometry and the new Hevylite™ methods; the first measures total IgM levels while the second one measures the immunoglobulin fractions bound to either kappa or lambda light chains therefore enabling us to determine the ratio of IgM-kappa/lambda (HLCR). Hevylite™ measurements were retrospectively performed in 69/188 patients with available frozen sera aliquots from drawn at the time of diagnosis. Of them the Ig subclasses IgMkappa and IgMlambda, IgGkappa and IgGlambda, IgAkappa and IgAlambda (HLC) were measured by Hevylite™ antibodies nephelometrically. Light chain restriction (kappa or lambda) was determined by flow cytometry or bone marrow/lymph node biopsy immunohistochemistry. The ratios (HLCRs) were calculate with the monoclonal immunoglobulin as numerator, i.e IgMkappa/IgMlambda, IgGkappa/IgGlambda and IgAkappa,/IgAlambda in kappa-restricted patients and IgMlambda/IgMkappa, IgGlambda/IgGkappa, IgAlambda/IgAkappa in lambda-ones. Serum IgM concentration by both methods were related to time to first treatment (TFT) and overall survival (OS). Statistical analysis was performed conventionally; survival curves were drawn by Kaplan-Meyer method and compared by the log-rank test. Results:Total IgM ranged from 12 to 246 mg/dl (median 47.6). The sum of IgMkappa plus IgMlambda from 12 to 369 (median 60). IgMkappa from 7.9 to 349 mg/dL (median 41) in kappa-restricted patients and IgMlambda from 7.6 ωζ 98 mg/dL (median 22) in lambda restricted ones. Low total IgM level (<50 mg/dL) was present in 52% of patients but it did not correlate to TFT or OS. Summated IgMkappa plus IgMlambda lower than 50 mg/dL was present in 41% and correlated with worse OS (p=0.016). Furthermore non-clonal IgM subclass suppression correlated with TFT (p=0.019) and OS (p=0.021). The same was not confirmed for non-clonal IgG and IgA subclasses suppression.Finally IgM-HLCR was abnormal in 35% of patients. Of them, 25% had also abnormal IgG-HLCR and/or IgA-HLCRs leading to the hypothesis of multiple clones coexistence within the neoplastic B-cell lymphocytic population. Conclusions:Low IgM levels determined by novel immunoassays (Hevylite™) correlate to shorter TFT and OS in patients with CLL. Their use may reveal new disease characteristic and are suggestive of a multi-oligoclonal disorder. Disclosures:No relevant conflicts of interest to declare.

Comparison of immunological parameters in patients with pemphigus vulgaris following rituximab and IVIG therapy

Information on certain immunological parameters in patients with pemphigus vulgaris (PV) treated with rituximab (RTX) and intravenous immunoglobulin (IVIG) therapy is limited. Comparing immunological parameters in patients who achieved long-term clinical remission (LTR) with those who relapsed. Retrospective analysis of 19 patients treated at a single centre using the same protocol. Comparisons were made between patients who went into LTR and those who relapsed following completion of the protocol. Treatments prior to IVIG and RTX included prednisone with or without an immunosuppressive agent. The immunological parameters measured included peripheral blood B cells (CD19+), serum quantitative immunoglobulin levels, and levels of antibodies to desmogleins (Dsg) 1 and 3. Eleven patients achieved LTR. Eight patients developed 15 relapses. The mean follow-up time for the LTR group was 29·6±11·2months, and for the relapse group, 40·0±7·0 months. There were no significant differences in times to B-cell depletion, repopulation, or recovery to pretreatment levels between the patients who achieved LTR and those who relapsed. Recurrences usually occurred after B-cell repopulation. Repeated treatments did not influence the time to B-cell repopulation. IgM levels were decreased after therapy and remained decreased. A consistent increase in anti-Dsg1 antibody levels occurred at the time of relapse in patients with mucocutaneous disease. The majority of patients treated with rituximab and IVIG therapy achieved LTR. Retreatment of relapses can induce LTR. Decreased serum IgM levels persisted following treatment. Increases in anti-Dsg1 antibodies during therapy in patients with mucocutaneous disease suggests a close follow-up for a potential relapse is required.

Pitfalls of “hyper”-IgM syndrome: a new CD40 ligand mutation in the presence of low IgM levels. A case report and a critical review of the literature

Here, we report on a male infant with low serum IgG, IgA and IgM levels who suffered from Pneumocystis jirovecii and cytomegalovirus (CMV) pneumonia. The patient was tested to be HIV-negative. Absolute and relative numbers of lymphocyte subsets were normal, excluding the diagnosis of an X-linked agammaglobulinaemia (Bruton's disease). Despite the decreased serum IgM level, an X-linked hyper-IgM syndrome (X-HIGM) was considered. X-HIGM is a rare immunodeficiency usually characterised by recurrent severe opportunistic infections, low serum IgG and IgA, but normal or increased serum IgM. The syndrome is caused by mutations of the CD40 ligand (CD40L) gene. In our patient, CD40L mutation analysis proved a novel mutation at codon 257 associated with non-detectable expression of CD40L on the surface of activated T cells. A literature search revealed that approximately 6.4% of X-HIGM patients had been found to have low serum IgM levels. Our statistical analysis of the IgM levels as reported by different studies arouses suspicion that many patients with low IgM levels may not have undergone diagnostic procedures for X-HIGM. In summary, in this report and critical review of the literature, we described a new mutation of CD40L and highlighted the pitfalls of the diagnosis of X-HIGM.

Ophthalmologic Techniques to Assess the Severity of Hyperviscosity Syndrome and the Effect of Plasmapheresis in Patients with Waldenström's Macroglobulinemia

BackgroundThe aim of this study is to determine the serum immunoglobulin (Ig) M and serum viscosity (SV) levels at which retinal changes associated with hyperviscosity syndrome (HVS) as a result of Waldenström's macroglobulinemia (WM) occur. In addition, the effect of plasmapheresis on HVS-related retinopathy was tested. Patients and MethodsA total of 46 patients with WM received indirect ophthalmoscopy, laser Doppler retinal blood flow measurements, serum IgM, and SV determinations. A total of 9 patients with HVS were studied before and after plasmapheresis. ResultsMean IgM and SV levels of patients with the earliest retinal changes were 5442 mg/dL and 3.1 cp, respectively. Plasmapheresis improved retinopathy, decreased serum IgM (46.5 ± 18%; P = .0009), SV (44.7 ± 17.3%; P = .002), retinal venous diameter (15.3 ± 5.8%; P = .0001), and increased venous blood speed by +55.2 ± 22.5% (P = .0004). ConclusionExamination of the retina is useful in identifying the symptomatic threshold of plasma viscosity levels in patients with HVS and can be used to gauge the effectiveness of plasmapheresis treatment.

Transgenic Mice Expressing Dominant-Negative Bright Exhibit Defects in B1 B Cells

The transcription factor Bright up-regulates Ig H chain production from select V region promoters and requires Bright dimerization, Bruton's tyrosine kinase (Btk), and the Btk substrate, TFII-I, for this activity. Defects in Btk cause X-linked immunodeficiency disease in mice and humans. Btk-deficient mice exhibit decreased serum IgM production, B cell developmental blocks, absence of peritoneal B1 cells, and subnormal immune responses against Ags, including phosphorylcholine, which confer protection against Streptococcus pneumoniae. Transgenic mice expressing dominant-negative Bright share similarities with Btk-deficient mice, including decreased serum IgM, poor anti-phosphorylcholine responses, and slightly reduced numbers of mature B cells. Although dominant-negative Bright mice developed B1 B cells, these were functionally deficient in Ig secretion. These data suggest a mechanistic explanation for the abnormal responses to phosphorylcholine observed in Btk-deficient mice, and indicate that Bright functions in a subset of Btk-dependent pathways in vivo, particularly those responses dominated by B1 B cells.

Long-term treatment with 5,5-diphenylhydantoin reduces lymphadenopathy and anti-ssDNA autoantibodies in C57BL/6- lpr/ lpr mice

To further the insight in the immunomodulating properties of the anticonvulsant 5,5-diphenylhydantoin (DPH), C57BL/6 (B6), C57BL/6- lpr/ lpr (B6- lpr/ lpr) and MRL/MpJ-+/+ (MRL) mice received DPH orally for six months to determine weekly urinary biopterin levels, a potential T-cell activation marker, by high performance liquid chromatography. At the end of the experiment serum antibody levels were measured by ELISA and relative lymphoid organ weights determined. DPH treatment resulted in reduced body weight in all strains, reduced spleen weights in B6 and MRL mice, profoundly reduced popliteal lymph node weights in B6- lpr/ lpr mice and increased thymus weights in MRL mice. DPH treatment decreased serum IgM, IgG and IgA as well as IgM and IgG anti-ssDNA levels in B6- lpr/ lpr mice, but did not affect these parameters in other strains. Effects of DPH on IgM rheumatoid factor levels in B6- lpr/ lpr mice were inconsistent. Urinary biopterin levels of untreated B6 and B6- lpr/ lpr mice were about equal and lower than those of MRL mice. During the first three months of DPH treatment, persistently elevated biopterin levels were observed in B6 and to a lesser degree in MRL mice, and alternately elevated and control levels in B- lpr/ lpr mice. Thereafter, the effects faded in all strains. Results show that long-term DPH treatment causes only minor lymphoid organ weight changes in B6 and MRL mice, but causes a clear reduction of the lymphadenopathy and (auto)antibody formation in B6- lpr/ lpr mice. Observed changes could not be related to altered biopterin excretion indicating that the latter is an inappropriate marker of murine autoimmune disease.

In vivo effects of hyperdiploid Ly-1+ B cells of NZB origin.

Cells with increased chromosome number and DNA content have been found in the spleens of old NZB mice. These hyperdiploid cells are of clonal origin and demonstrate discrete IgH chain gene rearrangements by Southern blot analysis. In this report, hyperdiploid cells were analyzed by three-color flow cytometric techniques and found to be Ly-1+ B cells which were dull for Ly-1 and bright for surface IgM. These cells, unlike typical diploid Ly-1+ B cells, were negative for B220/6B2 and surface IgD. Hyperdiploid Ly-1+ B cells were found to be the predominant splenic subpopulation in animals receiving a spleen cell transfer from donors which possessed hyperdiploid Ly-1+ B cells. (NZB x DBA/2)F1 recipients of NZB spleen cells demonstrated a 10- to 1000-fold increase in Ly-1+ B cells in the spleen but showed no increased levels of Ly-1+ B cells in the peritoneum. Nearly all the splenic Ly-1+ B cells were hyperdiploid with the phenotype of the NZB parent. Cytogenetic analysis revealed that all the hyperdiploid cells were NZB donor cells. These findings suggest that the increase in splenic Ly-1+ B cells in the F1 recipients was due to expansion of injected splenic hyperdiploid Ly-1+ B cells of NZB origin. All of the F1 recipients of NZB hyperdiploid Ly-1+ B cells demonstrated a significant decrease in endogenous B cells as well as decreased serum IgM and anti-ssDNA autoantibodies. These studies suggest that hyperdiploid Ly-1+ B cells are different from typical peritoneal Ly-1+ B cells both in the lymphoid organs to which they home and in their proliferative capacity. NZB hyperdiploid Ly-1+ B cells, which may arise as a natural consequence of hyperactive Ly-1+ B cells, may play an immunoregulatory role in the spleen.

Immunoglobulin gene expression in xid mice: Defective expression of secreted and membrane α-heavy chain RNA

CNA/N mice bearing the X-linked immunodeficiency ( xid) gene(s) demonstrate overall decreased numbers of B-cells, impaired immune responses to TI-2 antigens and decreased serum IgM, IgG3 and to a lesser extent IgG1 and IgA. In these experiments we examined equal numbers of B-cells (cells capable of regeneration of surface Ig) from PP, MLN and spleens of xid and control mice for immunoglobulin gene expression. B-cells present in CBA/N mice exhibit control levels of Ig isotypespecific mRNA accumulation and transcription. Oligonucleotide probes directed against membrane and secreted exons of β, γ and α genes were synthesized and hybridized to B-cell RNA from CBA/N and CBA/J mice to determine relative levels of each isotype- and exon-specific mRNA. Results revealed decreased α sRNA:α mRNA in splenic B-cells of xid mice when compared to control animals. Northern blot analysis of total tissue polysomal RNA demonstrated enhanced expression of the (larger) membrane form of α-mRNA (α m-RNA) of CBA/N when compared to CBA/J mice. This was especially apparent in splenic preparations; these and other studies have shown that both control and xid PP and MLN express enhanced levels of the membrane forms of each Ig heavy chain isotype RNA when compared to splenic RNA levels. These data suggest the presence of a defective regulation of membrane and secreted α in B-cell subpopulations of xid mice.

Analysis of leucocyte differentiation antigens in blood and bone marrow from patients with Waldenström's macroglobulinaemia.

Peripheral blood and bone marrow mononuclear cells from 10 patients with newly diagnosed Waldenström's macroglobulinaemia were analysed for the presence of leucocyte differentiation antigens using flow cytometry. Most patients had circulating intracytoplasmic-mu cells that were positive for the B-cell specific antigens B1, B2 and B4 and for the plasma cell antigen PCA-1. When such monoclonal cyto-mu + cells were purified by immune rosette depletion they were shown to express B1 to a much lesser extent than B2, B4 and PCA-1. In bone marrow samples cells with a similar phenotype, but with higher B1 expression were found in all patients. When the serum IgM paraprotein concentrations were compared to surface markers longitudinally from presentation and during the first courses of chemotherapy, a decreased serum IgM level was accompanied by a decrease in B1 cells in peripheral blood. These data demonstrate that WM cells possess a unique phenotype with coexpression of B-cell and plasma cell associated antigens.

In vitro immunoglobulin synthesis of the peripheral blood and synovial lymphocytes in patients with rheumatoid arthritis

The synthesis of immunoglobulins (IgG, IgA and IgM) by mononuclear cells (MNC) from peripheral blood and synovial fluid in patients with rheumatoid arthritis (RA) was studied emploing radioimmunoassay. The correlations between Ig synthesis rates and clinical data were also studied.The decreased synthesis of IgM by peripheral MNC, and of IgA by synovial fluid MNC, was characteristic of RA patients. A coincidence was found between the synthesis of IgM by peripheral MNC and the decreased serum IgM levels in RA patients. Furthermore, significant correlation was found between IgM synthesis rates by synovial fluid MNC and (a) blood sedimentation rate and (b) sensitized sheep red blood cell agglutination test. In contrast, Igsynthesis rates by peripheral blood MNC did not correlate with the clinical data. These data suggest the significant role of the synovial fluid MNC.

Transfer of agammaglobulinemia in the chicken: II. Characterization of the target of suppression

The T-independent adoptive primary and secondary responses of FP chicken spleen cells to B. abortus (BA) were suppressed by simultaneously transferred histocompatible spleen cells from agammaglobulinemic (Aγ) chickens previously injected with bursa cells. The response of spleen cells transferred with BA 2 days prior to suppressor cells was partially inhibited. Highly significant suppression of both 19 S and 7 S antibody formation was seen during the second week after memory cell transfer. When suppressor cells and primed spleen cells were transferred together and challenged with BA 2 weeks later the secondary responses were more inhibited in recipients that showed persistently decreased serum IgM than in those showing recovery toward normal IgM levels. Transfer of histocompatible suppressor cells into surgically bursectomized (SBX). irradiated, 4-week-old SC and FP strain recipients caused reduction or complete disappearance of serum IgM and lowered IgG levels, which correlated well with a decrease in plasma cell numbers in spleen and trident. Many recipients of both strains, examined 1 to 2 weeks after transfer, completely lacked plasma cells from gut-associated lymphoid tissues and from spleen. When such animals had been sensitized to BA prior to transfer and were challenged after recovery from suppression, they showed good secondary responses. Experiments with serially transferred memory cells using suppressed intermediate hosts also indicated survival of such cells in the face of marked suppression of antibody synthesis. Bursa follicles that were not destroyed by irradiation did not show any effect of the suppressor cells, although plasma cells often disappeared from the interfollicular areas. Intact irradiated recipients showed a greater tendency toward recovery from suppression than did SBX recipients. Although Ig-bearing cells in spleen and peripheral blood of suppressed animals were significantly lower than in irradiated SBX controls, they never disappeared as completely as did plasma cells and serum IgM. The results suggest a direct effect of suppressor cells on antibody-forming cells with a less marked effect on their precursors.