Influence of pre-B cell receptor deficiency on the immunoglobulin repertoires in peripheral blood B cells before and after immunization.

During B cell development, pre-B cell receptor (pre-BCR), comprising the immunoglobulin heavy chain (HC) and surrogate light chain (SLC), plays a crucial role. The expression of pre-BCR serves as a certification of HC quality, confirming its ability to associate with the SLC and light chain (LC). In mice lacking SLC, the absence of this quality control mechanism leads to a distorted repertoire of HCs in the spleen and bone marrow. In this study, we conducted a comparative analysis of the immunoglobulin gene repertoire in peripheral blood cells of both wild-type mice and pre-BCR-deficient mice. Our findings reveal differences not only in the µ HC repertoire but also in the α HC and κ LC repertoires of the pre-BCR-deficient mice. These results suggest that the pre-BCR-mediated quality check of HC influences the selection of class-switched HC and LC repertoires. To further explore the impact of pre-BCR deficiency, we immunized these mice with thymus-dependent antigens and compared the antigen-responding repertoires. Our observations indicate that the affinity maturation pathways remain consistent between wild-type mice and pre-BCR-deficient mice, albeit with variations in the degree of maturation.

[Expression of IGLL1 Gene and Its Clinical Significance in Pediatric T-ALL].

OBJECTIVE: To detect the relative expression of IGLL1 (immunoglobulin lambda-like polypeptide 1) mRNA in bone marrow of children with T-cell acute lymphoblastic leukemia (T-ALL), and analyze its correlation with the clinical characteristics and prognosis of the patients, so as to clarify the clinical significance of IGLL1 in pediatric T-ALL patients. METHODS: A total of 56 pediatric T-ALL patients hospitalized in Children's Hospital of Soochow University from June 2012 to December 2017 and treated with CCLG-ALL 2008 regimen were selected. Transcriptome sequencing technology was used to detect the transcription level of IGLL1 gene in children with T-ALL. According to 25% of the IGLL1 transcription level (cutoff value:448), the enrolled children were divided into IGLL1 low expression group (17 cases) and IGLL1 high expression group (39 cases). Combined with clinical data, the correlation between the expression level of IGLL1 and prognosis of the patients was analyzed. RESULTS: The comparative analysis showed that the transcription level of IGLL1 was not correlated with the clinical characteristics of the patients, such as sex, age, bone marrow blast, white blood cell (WBC) count at initial diagnosis. The 5-year OS rate of patients with high IGLL1 expression was significantly higher than that of patients with low IGLL1 expression (76.9%±6.7% vs 47.1%±12.1%, P =0.018). Further comparison of relapse-free survival (RFS) rate between the two groups showed that the 5-year RFS rate of patients with high IGLL1 expression was higher than that of patients with low IGLL1 expression, but the difference between the two groups was not statistically significant (P =0.095). Multivariate COX analysis was conducted on common clinical prognostic factors (age, sex, WBC count at diagnosis, prednisone response on the 7th day, bone marrow response on the 15th day after treatment) and IGLL1 expression level, and the results showed that IGLL1 expression (P =0.012) and prednisone response (P =0.017) were independent risk factors for overall survival in pediatric T-ALL patients. CONCLUSION: In pediatric T-ALL, the OS rate of children with high expression of IGLL1 gene was significantly higher than that of children with low expression of IGLL1 gene, and the expression level of IGLL1 gene was an independent factor affecting the survival of children with T-ALL, which suggests that IGLL1 is a marker of good clinical prognosis of children with T-ALL.

Expression of IGLL1 Gene and Its Clinical Significance in Pediatric T-ALL / 中国实验血液学杂志

OBJECTIVE@#To detect the relative expression of IGLL1 (immunoglobulin lambda-like polypeptide 1) mRNA in bone marrow of children with T-cell acute lymphoblastic leukemia (T-ALL), and analyze its correlation with the clinical characteristics and prognosis of the patients, so as to clarify the clinical significance of IGLL1 in pediatric T-ALL patients.@*METHODS@#A total of 56 pediatric T-ALL patients hospitalized in Children's Hospital of Soochow University from June 2012 to December 2017 and treated with CCLG-ALL 2008 regimen were selected. Transcriptome sequencing technology was used to detect the transcription level of IGLL1 gene in children with T-ALL. According to 25% of the IGLL1 transcription level (cutoff value:448), the enrolled children were divided into IGLL1 low expression group (17 cases) and IGLL1 high expression group (39 cases). Combined with clinical data, the correlation between the expression level of IGLL1 and prognosis of the patients was analyzed.@*RESULTS@#The comparative analysis showed that the transcription level of IGLL1 was not correlated with the clinical characteristics of the patients, such as sex, age, bone marrow blast, white blood cell (WBC) count at initial diagnosis. The 5-year OS rate of patients with high IGLL1 expression was significantly higher than that of patients with low IGLL1 expression (76.9%±6.7% vs 47.1%±12.1%, P =0.018). Further comparison of relapse-free survival (RFS) rate between the two groups showed that the 5-year RFS rate of patients with high IGLL1 expression was higher than that of patients with low IGLL1 expression, but the difference between the two groups was not statistically significant (P =0.095). Multivariate COX analysis was conducted on common clinical prognostic factors (age, sex, WBC count at diagnosis, prednisone response on the 7th day, bone marrow response on the 15th day after treatment) and IGLL1 expression level, and the results showed that IGLL1 expression (P =0.012) and prednisone response (P =0.017) were independent risk factors for overall survival in pediatric T-ALL patients.@*CONCLUSION@#In pediatric T-ALL, the OS rate of children with high expression of IGLL1 gene was significantly higher than that of children with low expression of IGLL1 gene, and the expression level of IGLL1 gene was an independent factor affecting the survival of children with T-ALL, which suggests that IGLL1 is a marker of good clinical prognosis of children with T-ALL.

Evolution of surrogate light chain in tetrapods and the relationship between lengths of CDR H3 and VpreB tails.

In the mammalian immune system, the surrogate light chain (SLC) shapes the antibody repertoire during B cell development by serving as a checkpoint for production of functional heavy chains (HC). Structural studies indicate that tail regions of VpreB contact and cover the third complementarity-determining region of the HC (CDR H3). However, some species, particularly bovines, have CDR H3 regions that may not be compatible with this HC-SLC interaction model. With immense structural and genetic diversity in antibody repertoires across species, we evaluated the genetic origins and sequence features of surrogate light chain components. We examined tetrapod genomes for evidence of conserved gene synteny to determine the evolutionary origin of VpreB1, VpreB2, and IGLL1, as well as VpreB3 and pre-T cell receptor alpha (PTCRA) genes. We found the genes for the SLC components (VpreB1, VpreB2, and IGLL1) only in eutherian mammals. However, genes for PTCRA occurred in all amniote groups and genes for VpreB3 occurred in all tetrapod groups, and these genes were highly conserved. Additionally, we found evidence of a new VpreB gene in non-mammalian tetrapods that is similar to the VpreB2 gene of eutherian mammals, suggesting VpreB2 may have appeared earlier in tetrapod evolution and may be a precursor to traditional VpreB2 genes in higher vertebrates. Among eutherian mammals, sequence conservation between VpreB1 and VpreB2 was low for all groups except rabbits and rodents, where VpreB2 was nearly identical to VpreB1 and did not share conserved synteny with VpreB2 of other species. VpreB2 of rabbits and rodents likely represents a duplicated variant of VpreB1 and is distinct from the VpreB2 of other mammals. Thus, rabbits and rodents have two variants of VpreB1 (VpreB1-1 and VpreB1-2) but no VpreB2. Sequence analysis of VpreB tail regions indicated differences in sequence content, charge, and length; where repertoire data was available, we observed a significant relationship between VpreB2 tail length and maximum DH length. We posit that SLC components co-evolved with immunoglobulin HC to accommodate the repertoire - particularly CDR H3 length and structure, and perhaps highly unusual HC (like ultralong HC of cattle) may bypass this developmental checkpoint altogether.

Loss of early B cell protein λ5 decreases bone mass and accelerates skeletal aging.

The early B cell protein λ5 is an essential component of the surrogate light chain and the preB cell receptor (preBCR), which is critical for optimal B cell development. To investigate the effect of λ5 and/or B cells on bone acquisition over time, we developed a panel of JH -/- , λ5-/-, JH -/- λ5-/-, and wild-type (WT) BALB/c mice and then studied postnatal bone development and aging in these mice at one, six, twelve, and twenty-two months of age. The trabecular bone volume over total volume (BV/TV) in JH -/- mice was similar to WT mice at all ages. In contrast, at six months of age and thereafter, λ5-/- and JH -/- λ5-/- mice demonstrated a severe decrease in trabecular bone mass. Surprisingly, bone mass in six-month-old λ5-/- and JH -/- λ5-/- mice was similar to or even lower than in aged (twenty-two-months) WT mice, suggesting accelerated skeletal aging. The postnatal development and the acquisition of cortical bone mass in JH -/- λ5-/- mice were generally comparable to WT. However, JH -/- λ5-/- mice showed a significant decrease in cortical BV/TV at six- and twelve months of age. To examine the contribution of λ5 and B cells to postnatal bone synthesis, we separately transplanted whole bone marrow cells from JH -/- λ5-/- and WT mice into irradiated JH -/- λ5-/- and WT recipients. WT recipients of JH -/- λ5-/- marrow cells failed to show acquisition of trabecular bone mass, whereas transplanting WT marrow cells into JH -/- λ5-/- recipients led to the recovery of trabecular bone mass. Transfer of WT marrow cells into JH -/- λ5-/- mice promoted synthesis of new cortical and trabecular bone. Our findings indicate that λ5 plays a major role in preserving bone mass during postnatal development and skeletal aging which is distinct from its role in B cell development. The absence of both λ5 and B cells in JH -/- λ5-/- mice leads to delayed acquisition of cortical bone during postnatal development. Dissecting the mechanism(s) by which λ5 regulates bone homeostasis may provide new avenues for the treatment of age-related loss of bone mass and osteoporosis.

Mutational Analysis of the VPREB1 Gene of Pre-BCR Complex in a Cohort of Sporadic Pediatric Patients With B-Cell Acute Lymphoblastic Leukemia.

During bone marrow B-cell development, the pre-B-cell receptor is formed by the association of the immunoglobulin heavy chain with a surrogate light chain, which is encoded by the VPREB1, and λ5 genes. It is known that pre-BCR signaling signifies a critical checkpoint at the pre-B-cell stage. Thus, failure pre-BCR signaling is proposed as a critical factor for the development of B-cell acute lymphoblastic leukemia (B-ALL). B­ALL is the most common pediatric cancer and is one of the leading causes of death in children. Until now, several molecular analyses were performed for genomic alterations in B-ALL, but for genomic analysis of the VPREB1 gene and its rare variations, limited studies have been conducted. In this study, using polymerase chain reaction and direct sequencing of 88 pediatric patients with B-ALL, we investigated the genomic region of the VPREB1 gene to find sequence variations of this gene. Our study presented ten homozygous and heterozygous point mutations and heterozygous nucleotide deletions, in the VPREB1 gene in 36 boys and 32 girls' patients. Our Bioinformatics assay results presented that these variations may alter the RNA folding, protein structure, and therefore probable effect on the protein function. These results propose that nucleotide changes probably contribute to B-ALL pathogenesis.

Comparative Aspects of Immunoglobulin Gene Rearrangement Arrays in Different Species.

Studies in humans and mice indicate the critical role of the surrogate light chain in the selection of the productive immunoglobulin repertoire during B cell development. However, subsequent studies using mutant mice have also demonstrated that alternative pathways are allowed. Our recent investigation has shown that some species, such as pig, physiologically use preferential rearrangement of authentic light chains, and become independent of surrogate light chains. Here we summarize the findings from swine and compare them with results in other species. In both groups, allelic and isotypic exclusions remain intact, so the different processes do not alter the paradigm of B-cell monospecificity. Both groups also retained some other essential processes, such as segregated and sequential rearrangement of heavy and light chain loci, preferential rearrangement of light chain kappa before lambda, and functional κ-deleting element recombination. On the other hand, the respective order of heavy and light chains rearrangement may vary, and rearrangement of the light chain kappa and lambda on different chromosomes may occur independently. Studies have also confirmed that the surrogate light chain is not required for the selection of the productive repertoire of heavy chains and can be substituted by authentic light chains. These findings are important for understanding evolutional approaches, redundancy and efficiency of B-cell generation, dependencies on other regulatory factors, and strategies for constructing therapeutic antibodies in unrelated species. The results may also be important for explaining interspecies differences in the proportional use of light chains and for the understanding of divergences in rearrangement processes. Therefore, the division into two groups may not be definitive and there may be more groups of intermediate species.

VpreB surrogate light chain expression in B-lineage ALL: a report from the Children's Oncology Group.

Immunotherapies directed against B-cell surface markers have been a common developmental strategy to treat B-cell malignancies. The immunoglobulin heavy chain surrogate light chain (SLC), comprising the VpreB1 (CD179a) and Lamda5 (CD179b) subunits, is expressed on pro- and pre-B cells, where it governs pre-B-cell receptor (BCR)-mediated autonomous survival signaling. We hypothesized that the pre-BCR might merit the development of targeted immunotherapies to decouple "autonomous" signaling in B-lineage acute lymphoblastic leukemia (B-ALL). We used the Children's Oncology Group (COG) minimal residual disease (MRD) flow panel to assess pre-BCR expression in 36 primary patient samples accrued to COG standard- and high-risk B-ALL studies through AALL03B1. We also assessed CD179a expression in 16 cases with day 29 end-induction samples, preselected to have ≥1% MRD. All analyses were performed on a 6-color Becton-Dickinson flow cytometer in a Clinical Laboratory Improvement Amendment/College of American Pathologist-certified laboratory. Among 36 cases tested, 32 cases were at the pre-B and 4 cases were at the pro-B stages of developmental arrest. One or both monoclonal antibodies (mAbs) showed that CD179a was present in ≥20% of the B-lymphoblast population. All cases expressed CD179a in the end-induction B-lymphoblast population. The CD179a component of the SLC is commonly expressed in B-ALL, regardless of genotype, stage of developmental arrest, or National Cancer Institute risk status.

An in-depth analysis reveals two new genetic variants on 22q11.2 associated with vitiligo in the Chinese Han population.

BACKGROUND: Vitiligo is a complex disease in which patchy depigmentation is the result of an autoimmune-induced loss of melanocytes in affected regions. On the basis of a genome-wide linkage analysis of vitiligo in the Chinese Han population, we previously showed significant evidence of a linkage between 22q12 and vitiligo. Our aim in the current study was to identify vitiligo susceptibility variants within an expanded region of the 22q12 locus. METHODS AND RESULTS: An in-depth analysis of the expanded region of the 22q12 locus was performed by imputation using a large GWAS dataset consisting of 1117 cases and 1701 controls. Eight nominal SNPs were selected and genotyped in an independent cohort of Chinese Han individuals (2069 patients and 1370 control individuals) by using the Sequenom MassArray iPLEX1 system. The data were analyzed with PLINK 1.07 software. The C allele of rs730669 located in ZDHHC8/RTN4R showed a strong association with vitiligo (P = 3.25 × 10-8, OR = 0.81). The C allele of rs4820338 located in VPREB1 and the A allele of rs2051582 (a SNP reported in our previous study) located in IL2RB showed a suggestive association with vitiligo (P = 1.04 × 10-5, OR = 0.86; P = 1.78 × 10-6, OR = 1.27). The three identified SNPs showed independent associations with vitiligo in a conditional logistic regression analysis (all P < 1.0 × 10-5; all D' < 0.05 and r2 < 1.0 × 10-4). CONCLUSIONS: The study reveals that two novel variants rs730669 (ZDHHC8/RTN4R) and rs4820338 (VPREB1) on 22q11.2 might confer susceptibility to vitiligo and affect disease subphenotypes. The presence of multiple independent variants emphasizes their important roles in the genetic pathogenesis of disease.

IGLL5 is correlated with tumor-infiltrating immune cells in clear cell renal cell carcinoma.

Renal cell carcinomas (RCCs) account for about 90% of renal tumors, and their major histological subtype is ccRCC (clear cell RCC). Increasing evidence has indicated that the tumor microenvironment plays a significant role in the occurrence and development of ccRCC. In this study, we used ESTIMATE and CIBERSORT computational methods to calculate the proportion of immune and stromal components and the rate of TICs (tumor-infiltrating immune cells) in 539 ccRCC samples from The Cancer Genome Atlas database. By examining the intersection of the differentially expressed genes obtained by the protein-protein interaction network and Cox regression analysis, we identified only one overlapping gene: IGLL5 (immunoglobulin lambda-like polypeptide 5). We report that IGLL5 expression is correlated with TICs. Furthermore, our immunoinfiltration analyses revealed that three types of TIC are positively correlated with IGLL5 expression. IGLL5 may have potential as a prognostic biomarker of ccRCC.

CRISPR/Cas9 mediated knock-out of VPREB1 gene induces a cytotoxic effect in myeloma cells.

BACKGROUND: Multiple Myeloma (MM) is a heterogeneous, hematological neoplasm that accounts 2% of all cancers. Although, autologous stem cell transplantation and chemotherapy are currently the most effective therapy, it carries a notable hazards, in addition for being non curative. Recently, the Clustered Regular Interspaced Short Palindromic Repeats (CRISPR-cas9) has been successfully tried at the experimental level, for the treatment of several hematological malignancies. OBJECTIVES: We aimed to investigate the in-vitro effect of CRISPR-cas9-mediated knock-out of V-set pre B-cell surrogate light chain 1"VPREB1" gene on the malignant proliferation of primary cultured myeloma cells. METHODS: Bioinformatics' analysis was performed to explore the gene expression profile of MM, and the VPREB1 gene was selected as a target gene for this study. We knocked-out the VPREB1 gene in primary cultured myeloma cells using CRISPR-cas9, the VPREB1 gene editing efficacy was verified by determining VPREB1 gene expression at both the mRNA and protein levels by qPCR and immunofluorescence, respectively. Furthermore, the cytotoxic effect on primary myeloma cells proliferation was evaluated using cytotoxicity assay. RESULTS: There was a statistically significant reduction of both VPREB1 mRNA and protein expression levels (p<0.01). knock-out of VPREB1 gene in myeloma cell line resulted in a statistically significant reduction of myeloma cell proliferation. CONCLUSION: CRISPR-cas9-mediated knock-out of VPREB1 gene is effective for inhibiting the proliferation of primary myeloma cells. This would provide a basis for a promising therapeutic strategy for patients with multiple myeloma.

Association of VPREB1 Gene Copy Number Variation and Rheumatoid Arthritis Susceptibility.

OBJECTIVE: Copy number variation (CNV) is a structural variation in the human genome that has been associated with multiple clinical phenotypes. B cells are important components of rheumatoid arthritis- (RA-) mediated immune response; hence, CNV in the regulators of B cells (such as VPREB1) can influence RA susceptibility. In this study, we aimed to explore the association of CNV in the VPREB1 gene with RA susceptibility in the Pakistani population. METHODS: A total of 1,106 subjects (616 RA cases, 490 healthy controls) were selected from three rheumatology centers in Pakistan. VPREB1 CNV was determined using the TaqMan® CN assay (Hs02879734_cn, Applied Biosystems, Foster City, CA, USA), and CNV was estimated by using CopyCaller® (version 2.1; Applied Biosystems, USA) software. Odds ratio (OR) was calculated by logistic regression with sex and age as covariates in R. RESULTS: A significant association between >2 VPREB1 CNV and RA risk was observed with an OR of 3.92 (95% CI: 1.27 - 12.12; p = 0.01746) in the total sample. Whereas <2 CNV showed a significantly protective effect against RA risk in women with an OR of 0.48 (95% CI: 0.29-0.79; p = 0.00381). CONCLUSION: CNV > 2 of VPREB1 is a risk factor for RA in the total Pakistani population, while CNV < 2 is protective in women.

Protein Network Analysis Identifies Changes in the Level of Proteins Involved in Platelet Degranulation, Proteolysis and Cholesterol Metabolism Pathways in AECOPD Patients.

Chronic obstructive pulmonary disease (COPD) is characterised by a progressive pulmonary and systemic inflammation. Acute exacerbations of COPD (AECOPD) are associated with acute inflammation and infection, increase in the rates of morbidity and mortality. Previous proteomic studies have focussed on identifying proteins involved in COPD pathogenesis in samples collected from the lung (e.g. lung tissue biopsies, bronchoalveolar lavage and sputum) but not from blood of patients who experienced AECOPD. In this study, plasma was analysed by two independent quantitative proteomics techniques; isobaric tag for relative and absolute quantitation (iTRAQ) and multiple reaction monitoring (MRM) to identify differential expression of circulating proteins in patients with stable COPD (sCOPD) and AECOPD. Firstly, iTRAQ performed on pooled plasma samples from AECOPD, sCOPD, and healthy non-smoking controls (HC) revealed 15 differentially expressed proteins between the 3 groups. MRM subsequently performed on a separate cohort of AECOPD, sCOPD, and HC patients confirmed 9 proteins to be differentially expressed by AECOPD compared to HC (Afamin, alpha-1-antichymotrypsin, Apolipoprotein E, Beta-2-glycoprotein 1, Complement component C9, Fibronectin, Immunoglobulin lambda like polypeptide 5, Inter-alpha-trypsin inhibitor heavy chain H3, Leucine rich alpha-2-glycoprotein 1). Network analysis demonstrates that most of these proteins are involved in proteolysis regulation, platelet degranulation and cholesterol metabolism. In conclusion, several potential plasma biomarkers for AECOPD were identified in this study. Further validation studies of these proteins may elucidate their roles in the development of AECOPD.

Surrogates for Identifying Pre-School Children with Iron Deficiency Anaemia: Is Red cell indices useful?

There are difficulties in determining children with iron deficiency anaemia in developing countries due to cost of serum ferritin estimation. We sought to determine the relationship between red cell indices and serum ferritin among pre-school children. A random sample of 89 apparently healthy children was recruited. Serum ferritin was measured by ELIZA while red cell indices were determined by auto-analysis.Correlations analysis was performed to test the relationship between serum ferritin and the red cell indices. Also validity testing of red cell indices as screening tools was performed using the sensitivity, specificity, and predictive values. Weak significant positive correlations were seen between serum ferritin and MCV, and MCH irrespective of the anaemic status of study subjects anaemia status (p = 0.020, and 0.040 respectively). Following stratification according to presence or absence of anaemia, a significant positive correlation was seen between serum ferritin and MCV among subjects with anaemia. None of the red cell indices were found to reach significant correlation levels with the red cell indices in non-anaemic study subjects. There were notable difference between sensitivity, specificity, and predictive values using MCV compared with MCH in the anaemic children. MCV was observed to be a useful surrogate for predicting iron deficiency state in pre-school children with anaemia where serum ferritin is not readily available

B-1a cells acquire their unique characteristics by bypassing the pre-BCR selection stage.

B-1a cells are long-lived, self-renewing innate-like B cells that predominantly inhabit the peritoneal and pleural cavities. In contrast to conventional B-2 cells, B-1a cells have a receptor repertoire that is biased towards bacterial and self-antigens, promoting a rapid response to infection and clearing of apoptotic cells. Although B-1a cells are known to primarily originate from fetal tissues, the mechanisms by which they arise has been a topic of debate for many years. Here we show that in the fetal liver versus bone marrow environment, reduced IL-7R/STAT5 levels promote immunoglobulin kappa gene recombination at the early pro-B cell stage. As a result, differentiating B cells can directly generate a mature B cell receptor (BCR) and bypass the requirement for a pre-BCR and pairing with surrogate light chain. This 'alternate pathway' of development enables the production of B cells with self-reactive, skewed specificity receptors that are peculiar to the B-1a compartment. Together our findings connect seemingly opposing lineage and selection models of B-1a cell development and explain how these cells acquire their unique properties.

Disruption of the preB Cell Receptor Complex Leads to Decreased Bone Mass.

In the bone marrow, preB cells are found adjacent to the bone endosteum where bone synthesizing osteoblast and bone resorbing osteoclasts reside. Although there is evidence of interactions between preB and bone cells, the factors that contribute to such interactions are poorly understood. A critical checkpoint for preB cell development assesses the integrity of the nascent immunoglobulin µ heavy chain (HC) by testing whether it can participate in the formation of a preB cell receptor (preBCR), composed of the µ HC and surrogate light chain (LC). In this work, we tested whether loss of preBCR components can affect bone synthesis. A panel of gene targeted mice with sequential blocks in preBCR formation or function [surrogate light chain component lambda 5 deleted (λ5-/-), transmembrane domain of µHC deleted (IgM-mem-/-), and CD19 preBCR co-receptor deleted (CD19-/-)] were evaluated for effects on postnatal bone synthesis. Postnatal bone mass was analyzed in 6 month old mice using µ-CT, histomorphometry and double calcein labeling. Both cortical and trabecular bone mass were significantly decreased in the femurs of the λ5 and IgM-mem deficient mice. Histomorphometric analysis showed a decrease in the numbers of osteoblasts and osteoclasts in all three mutant strains. Double calcein labeling revealed a significant decrease in dynamic synthesis and mineralization of bone in λ5-/- mice. Our data strongly suggest that interference with preBCR formation or function affects bone homeostasis independent of the presence or absence of mature B cells, and that components of the preBCR play important, and potentially distinct, roles in regulating adult bone mass.

The Role of the Pre-B Cell Receptor in B Cell Development, Repertoire Selection, and Tolerance.

Around four decades ago, it had been observed that there were cell lines as well as cells in the fetal liver that expressed antibody µ heavy (µH) chains in the apparent absence of bona fide light chains. It was thus possible that these cells expressed another molecule(s), that assembled with µH chains. The ensuing studies led to the discovery of the pre-B cell receptor (pre-BCR), which is assembled from Ig µH and surrogate light (SL) chains, together with the signaling molecules Igα and ß. It is expressed on a fraction of pro-B (pre-BI) cells and most large pre-B(II) cells, and has been implicated in IgH chain allelic exclusion and down-regulation of the recombination machinery, assessment of the expressed µH chains and shaping the IgH repertoire, transition from the pro-B to pre-B stage, pre-B cell expansion, and cessation.

Intrathecal K free light chain synthesis in multiple sclerosis at clinical onset associates with local IgG production and improves the diagnostic value of cerebrospinal fluid examination.

BACKGROUND: The pathological significance and the diagnostic usefulness of intrathecal κ and λ free light chain (FLC) synthesis in Multiple Sclerosis (MS) are debated. METHODS: Paired cerebrospinal fluid (CSF) and serum specimens from 70 relapsing remitting MS (RRMS), 40 with and 30 without CSF restricted IgG Oligoclonal Band (IgGOB), and 37 from healthy controls (HC) were analyzed. IgG, IgM, κFLC and λFLC concentrations and indexes were evaluated. All RRMS performed MRI to estimate white and grey matter (WM) pathology. RESULTS: In HC, no intrathecal κ or λ FLC synthesis was found, and κFLC and λFLC Indexes were reciprocally correlated (r = 0.67, p < 0.001). In RRMS, intrathecal κFLC or λFLC synthesis was demonstrated in respectively 66% and 43% of the cases, the Qκ/λ ratio was significantly higher compared to HC (17.0 ±â€¯31.3 vs 0.79 ±â€¯0.20, p < 0.001) and the correlation between κFLC Index and λFLC Index was weak (r:0.38, p < 0.05). Intrathecal IgG synthesis was associated with κFLC Index (IgG Index: r2 = 0.53, ß = 0.73, p < 0.001; IgGLOC: r2 = 0.37, ß = 0.61, p < 0.001; IgGIF: r2 = 0.69, ß = 0.83, p < 0.001), but not with λFLC Index, while intrathecal IgM synthesis correlated with λFLC Index (IgM Index: r = 0.41, p < 0.001; IgMLOC: r = 0.34, p < 0.005; IgMIF: r = 0.45, p < 0.001), but not with κFLC Index. 26% of RRMS patients without CSF-restricted IgGOB had increased κFLCLOC. Finally, no associations were observed between any CSF and MRI parameters. CONCLUSIONS: The demonstration of intrathecal κFLC synthesis may further improve the diagnostic usefulness of CSF examination in RRMS. The marked increased in Qκ/λ further suggests a deregulated B-cell activation in MS pathology.

Haemodiafiltration with ultrafiltrate regeneration in the removal of free light chains in multiple myeloma and acute kidney injury / Hemodiafiltración con regeneración de ultrafiltrado en la eliminación de cadenas ligeras libres en mieloma múltiple y lesión renal aguda

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A multiple myeloma-specific capture sequencing platform discovers novel translocations and frequent, risk-associated point mutations in IGLL5.

Multiple myeloma (MM) is a disease of copy number variants (CNVs), chromosomal translocations, and single-nucleotide variants (SNVs). To enable integrative studies across these diverse mutation types, we developed a capture-based sequencing platform to detect their occurrence in 465 genes altered in MM and used it to sequence 95 primary tumor-normal pairs to a mean depth of 104×. We detected cases of hyperdiploidy (23%), deletions of 1p (8%), 6q (21%), 8p (17%), 14q (16%), 16q (22%), and 17p (4%), and amplification of 1q (19%). We also detected IGH and MYC translocations near expected frequencies and non-silent SNVs in NRAS (24%), KRAS (21%), FAM46C (17%), TP53 (9%), DIS3 (9%), and BRAF (3%). We discovered frequent mutations in IGLL5 (18%) that were mutually exclusive of RAS mutations and associated with increased risk of disease progression (p = 0.03), suggesting that IGLL5 may be a stratifying biomarker. We identified novel IGLL5/IGH translocations in two samples. We subjected 15 of the pairs to ultra-deep sequencing (1259×) and found that although depth correlated with number of mutations detected (p = 0.001), depth past ~300× added little. The platform provides cost-effective genomic analysis for research and may be useful in individualizing treatment decisions in clinical settings.