Immunoglobulin-Like Transcript 2 (ILT2) Is Not Differentially Expressed in MGUS and Myeloma, but Appears To Be Downregulated at an Earlier Stage of Plasma Cell Disease.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 5039-5039
Author(s):  
Martin Schreder ◽  
Wolfgang Huebl ◽  
Gudrun Koch ◽  
Kathrin Strasser-Weippl ◽  
Niklas Zojer ◽  
...  
Keyword(s):  
Differential Expression ◽  
Plasma Cell ◽  
Plasma Cells ◽  
Killer Cell ◽  
Differentially Expressed ◽  
Expression Level ◽  
Prognostic Impact ◽  
Clinical Parameters ◽  
Mrna Levels ◽  
Normal Plasma

Abstract Background: Immunoglobulin-like transcript 2 (ILT2/CD85j) belongs to the Ig superfamily and has homology to the killer cell inhibitory receptors (KIRs). It is expressed on natural killer (NK) cells, monocytes, macrophages, dendritic cells and (naive) B lymphocytes. A differential expression of ILT2 was described for monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM). Gene expression profiling studies found ILT2 to be downregulated 8.26 fold in myeloma as compared to MGUS, being the most differentially expressed gene between these two subsets. However, as RNA from CD138+ cells was used in this analysis, a varying percentage of normal, non-malignant plasma cells will impact on the results, especially in MGUS cases. Aims: We aimed to delineate ILT2 expression in different plasma cell subsets (normal compared to monoclonal cells) in MGUS and MM and the eventual prognostic impact of a differential expression level. Methods: ILT2 expression was measured by flow cytometry using a PE-conjugated antibody (clone HP-F1, Beckman Coulter) in a series of 30 MGUS patients and 91 myeloma patients. Phenotypically normal and malignant plasma cells were defined by differential expression of CD38, CD45, CD19 and CD56. Expression levels are given as mean fluorescence intensity (MFI) after correction for background staining. Results: ILT2 was not differentially expressed in monoclonal plasma cells from patients with MGUS (MFI median 112.0, range 13.5–274.4) and myeloma (MFI median 96.6, range 0.4–454.5). In contrast, monoclonal cells from MGUS and MM showed a significantly lower expression of ILT2 as compared to phenotypically normal plasma cells in the majority of samples (p=0.007). Results were confirmed by quantitative real time PCR studies in 25 MM patients showing a linear correlation of ILT2 mRNA levels with the intensity of ILT2 protein expression. ILT2 levels did not vary with state of disease and showed no correlation with clinical parameters or prognosis in our series of myeloma patients. Conclusions: In the majority of patients with monoclonal plasma cell disorders, ILT2 seems to be downregulated at an early stage of disease, i.e. upon transformation from a normal plasma cell to the MGUS/MM stage. The expression level of ILT2 in monoclonal plasma cells is neither correlated with the state of disease (MGUS versus newly diagnosed myeloma versus advanced disease) nor to prognosis of myeloma patients or other clinical parameters.

scholarly journals Appearance of Human Plasma Cells Following Differentiation of Human B Cells in NOD/SCID Mouse Spleen

2003 ◽  
Vol 10 (2-4) ◽  
pp. 197-202 ◽  
Author(s):  
Kentaro Kikuchi ◽  
Zhe-Xiong Lian ◽  
Xiao-Song He ◽  
Aftab A. Ansari ◽  
Miyuki Ishibashi ◽  
...  
Keyword(s):  
B Cells ◽  
Plasma Cell ◽  
Mononuclear Cells ◽  
Plasma Cells ◽  
Human Peripheral Blood ◽  
Natural Killer Cell Activity ◽  
Killer Cell ◽  
Cell Activity ◽  
Scid Mice ◽  
Human B Cells

Relatively little is known for the differentiation and maturation process of human B cells to plasma cells. This is particularly important in reconstitution work involving transfer of autoantibodies. To address this issue, we transplanted human peripheral blood mononuclear cells (PBMC) directly into the spleen of irradiated NOD/SCID mice depleted of natural killer cell activity. Within 6 weeks, naïve B cells differentiated into memory B cells and, importantly, the numbers of human CD138+plasma cells in spleen increased by 100 fold after transplantation. Plasma cell numbers correlated with the detection of human IgM and IgG in serum, indicating that human B cells had differentiated into mature plasma cells in the murine spleen. In addition to CD19+plasma cells, a distinct CD19-plasma cell population was detected, suggesting that downregulation of CD19 associated with maturation of plasma cells occurred. When purified human B cells were transplanted, those findings were not observed. Our results indicate that differentiation and maturation of human B cells and plasma cells can be investigated by transplantation of human PBMC into the spleen of NOD/SCID mice. The model will be useful for studying the differentiation of human B cells and generation of plasma cells.

scholarly journals MicroRNA and their target mRNAs change expression in whole blood of patients after intracerebral hemorrhage

2019 ◽  
Vol 40 (4) ◽  
pp. 775-786 ◽  
Author(s):  
Xiyuan Cheng ◽  
Bradley P Ander ◽  
Glen C Jickling ◽  
Xinhua Zhan ◽  
Heather Hull ◽  
...  
Keyword(s):  
Intracerebral Hemorrhage ◽  
Whole Blood ◽  
Killer Cell ◽  
Transcriptome Profiling ◽  
Rna Degradation ◽  
Differentially Expressed ◽  
Mrna Levels ◽  
Target Mrnas ◽  
Mrna Targets ◽  
Differentially Expressed Mirnas

Previous studies showed changes in mRNA levels in whole blood of rats and humans, and in miRNA in whole blood of rats following intracerebral hemorrhage (ICH). Thus, this study assessed miRNA and their putative mRNA targets in whole blood of humans following ICH. Whole transcriptome profiling identified altered miRNA and mRNA levels in ICH patients compared to matched controls. Target mRNAs of the differentially expressed miRNAs were identified, and functional analysis of the miRNA-mRNA targets was performed. Twenty-nine miRNAs (22 down, 7 up) and 250 target mRNAs (136 up, 114 down), and 7 small nucleolar RNA changed expression after ICH compared to controls (FDR < 0.05, and fold change ≥ |1.2|). These included Let7i, miR-146a-5p, miR210-5p, miR-93-5p, miR-221, miR-874, miR-17-3p, miR-378a-5p, miR-532-5p, mir-4707, miR-4450, mir-1183, Let-7d-3p, miR-3937, miR-4288, miR-4741, miR-92a-1-3p, miR-4514, mir-4658, mir-3689d-1, miR-4760-3p, and mir-3183. Pathway analysis showed regulated miRNAs/mRNAs were associated with toll-like receptor, natural killer cell, focal adhesion, TGF-β, phagosome, JAK-STAT, cytokine–cytokine receptor, chemokine, apoptosis, vascular smooth muscle, and RNA degradation signaling. Many of these pathways have been implicated in ICH. The differentially expressed miRNA and their putative mRNA targets and associated pathways may provide diagnostic biomarkers as well as point to therapeutic targets for ICH treatments in humans.

Association of a combined panel of tumor infiltrating lymphocytes, plasma cells, and macrophages with recurrence of localized clear cell (cc) renal cell carcinoma (RCC) undergoing surgery.

2016 ◽  
Vol 34 (2_suppl) ◽  
pp. 502-502
Author(s):  
Pooja Ghatalia ◽  
Jennifer Gordetsky ◽  
Sejong Bae ◽  
Stacey M Watkins ◽  
Sunil Sudarshan ◽  
...  
Keyword(s):  
Plasma Cell ◽  
Tumor Recurrence ◽  
Plasma Cells ◽  
Immune Cell ◽  
Tumor Infiltrating Lymphocytes ◽  
Macrophage Infiltration ◽  
Composite Panel ◽  
Prognostic Impact ◽  
Urologic Oncology ◽  
Risk Of Recurrence

502 Background: Tumor infiltrating Programmed-Death (PD)-1 and FoxP3-expressing lymphocytes and macrophages appear to be associated with higher risk of recurrence in patients (pts) with ccRCC undergoing surgery for localized disease. We aimed to combine the presence of morphologically identified lymphocytes, plasma cells and macrophages into a readily available composite immune cell panel and to evaluate its association with tumor recurrence. Methods: We identified pts with ccRCC who underwent nephrectomy at UAB for whom we had annotation for objective tumor recurrence and a minimum follow-up of 2 years. Central pathology review was conducted by a single urologic oncology certified pathologist to capture pathologic variables (stage, grade, necrosis, histologic components, cystic changes) and immune cell (lymphocyte/plasma cell/macrophage) infiltration. Logistic regression (univariate and multivariate) analyses were conducted to evaluate the association of these variables with tumor recurrence. Results: Of the 159 identified and evaluable pts, 33 (20.7%) recurred and 126 did not. On univariate analyses, sarcomatoid/rhabdoid histologic components, lymphocyte/plasma cell infiltration, necrosis, pathological T stage and histologic grade were all statistically significantly associated with a risk of recurrence (p < 0.05). On multivariate analysis, in addition to pathologic stage (p = 0.0018), only the combination of higher lymphocyte/plasma cell and macrophage infiltration (p = 0.0347) was independently associated with recurrence; patients were 8.7 times more likely to recur (95% CI: 1.66, 45.28). Conclusions: A readily available and widely applicable composite panel of morphologically identified lymphocytes, plasma cells and macrophages infiltrating the tumor predicts recurrence of pts with localized ccRCC undergoing surgery, after controlling for clinical and pathologic prognostic factors. Our hypothesis-generating data require validation and further interrogation of specific markers expressed on immune cells may refine an immune panel that confers prognostic impact.

Comparison of Newly Diagnosed and Relapsed Refractory Multiple Myeloma Using Transcriptional Profiling of Myeloma Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1555-1555
Author(s):  
Shaji Kumar ◽  
Philip R. Greipp ◽  
Jessica L. Haug ◽  
Michael Kline ◽  
Wee Joo Chng ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Drug Resistance ◽  
Differential Expression ◽  
Median Survival ◽  
Plasma Cell ◽  
Plasma Cells ◽  
Expression Profiles ◽  
Significant Proportion ◽  
Newly Diagnosed ◽  
Myeloma Cells

Abstract Background: Multiple myeloma (MM) is a plasma cell malignancy that is incurable with current approaches. The median survival for patients with MM is around four years and a significant proportion of patients experience a course characterized by multiple relapses treated with different therapies. The median survival for patients relapsing after the initial therapy is nearly 18 months and successive treatment strategies result in decreasing response durations, likely reflecting acquired drug resistance. In order to better understand the biological changes associated with advanced, relapsed, refractory MM, we compared gene expression profiles (GEP) of malignant plasma cells isolated from patients with relapsed refractory MM and compared them to plasma cells from patients with newly diagnosed MM. Methods: In order to obtain two relatively homogenous group of patients, we compared samples from 44 patient with newly diagnosed MM enrolled in the ECOG E1A00 clinical trial (comparing thalidomide and dexamethasone to dexamethasone alone) to 44 patients with relapsed refractory MM enrolled in a phase II trial of Velcade (SUMMIT), where most patients had four or more previous relapses. Plasma cells from bone marrow aspirates were separated by magnetic bead selection of CD138 positive cells and studied using Affymetrix HG-U133A chips using standard methodology. The arrays were analyzed using Genespring 7.2 software following GCRMA normalization and genes with differential expression between the two datasets were examined. Differentially expressed genes were further analyzed using Ingenuity Pathways Analysis program. Results: A total of 864 genes were identified which were at least two fold and significantly different between the newly diagnosed and relapsed patients. Using Ingenuity software, 437 of these genes were mapped to different biological networks. Examination of the canonical pathways demonstrated several important cellular pathways differentially regulated between the two groups. Several important mediators of the cytokines, receptors and respective signaling pathways appear to be down regulated in the relapsed group and included IGF-1, HGF, SDF-1 alpha, gp130 and importantly the MEK/ERK pathway. Additionally expression of adhesion molecules such as VCAM1 and PECAM was decreased in the relapsed group compared to newly diagnosed pts. There appear to increased tissue hypoxia in the relapsed marrow as indicated by up regulation of HIF-1 alpha as well increased levels of Placental growth factor. Myeloma cells from relapsed disease were characterized by decreased expression of mcl1, FLIP1, and bcl-xL and increased caspase 8 relative to newly diagnosed group. Also seen was decreased expression of the glucocorticoid and interferon receptors in the relapsed setting. Conclusion: Comparison of the GEP between MM cells from newly diagnosed and relapsed pts demonstrates important differences that have potential biological relevance. The plasma cell in the relapsed setting appears to be more independent of the tumor microenvironment. Additionally, differential expression of some of the genes provides clues to mechanisms of drug resistance commonly observed in the relapsed pts. We are in the process of validating some of the key findings from these analyses.

Identification of Genes Associated with Increased Bone Marrow Angiogenesis in Multiple Myeloma.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 5109-5109
Author(s):  
Michael Kline ◽  
S. Vincent Rajkumar ◽  
Jessica Haug ◽  
Linda Wellik ◽  
John A. Lust ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bone Marrow ◽  
Differential Expression ◽  
Plasma Cells ◽  
T Test ◽  
Differentially Expressed ◽  
Newly Diagnosed ◽  
Interacting Protein ◽  
Intracellular Channel ◽  
Transcribed Sequences

Abstract Introduction: Increased bone marrow angiogenesis is a characteristic feature of multiple myeloma (MM) and correlates with disease progression. Increased bone marrow angiogenesis at the time of diagnosis, measured in terms of microvessel density (MVD), is a powerful adverse prognostic factor for patients with MM. To better understand the biological basis of this phenomenon and to understand the mechanisms responsible for increased MVD in MM we compared the gene expression profiles of plasma cells from newly diagnosed MM patients with low and high MVD. Methods: Bone marrow biopsy sections from pts with newly diagnosed MM were studied using CD34 immunostaining and graded as low, intermediate, or high by MVD as previously described. 19 pts each, with low or high MVD were included for this study. RNA was isolated from CD138+ plasma cells of MM patients and analyzed using Affymetrix HG-U133A arrays. To examine differential expression, GC-RMA normalized data was analyzed using GeneSpring 7.2 software and genes with ≥ 2-fold differential expression between high and low MVD samples were identified. The Welch T-test was used to determine the significance of differential expression. Results and Conclusion: Expression of 42 transcripts was increased ≥ 2-fold in samples with high MVD in comparison to samples with low MVD. Of these transcripts, 14 were found to be significantly increased (P&lt;0.05) using the Welch T-test (see Table 1). Expression of 16 transcripts was decreased ≥ 2-fold in samples with high MVD in comparison to samples with low MVD. Of these transcripts, 6 were found to be significantly decreased (P&lt;0.05) using the Welch T-test (see Table 1). Genes differentially expressed include those involved in inhibiting apoptosis, facilitating IL-6 signaling, ion transport, extracellular matrix interaction, and regulating gene expression. Classical angiogenesis genes including VEGF, FGF, and IGF were not found to be differentially expressed (&gt; 2-fold). In conclusion, the list of differentially expressed genes reveals many functions relevant to MM disease pathology including proliferation, apoptosis, regulation of gene expression, cytokine signaling, and adhesion. Current studies evaluating the expression and function of these genes in relation to MM may identify factors critical for angiogenesis and MM progression and provide insight for therapeutic intervention. Gene Description Fold Change COL1A2 collagen, type I, alpha 2 3.008 MCL1 myeloid cell leukemia sequence 1 (BCL2-related) 2.793 209183_s_at chromosome 10 open reading frame 10 2.541 VIL2 villin 2 2.478 IL6ST interleukin 6 signal transducer (gp130) 2.404 CLIC2 chloride intracellular channel 2 2.364 DEPDC6 DEP domain containing 6 2.35 PBXIP1 pre-B-cell leukemia transcription factor interacting protein 1 2.337 CLIC4 chloride intracellular channel 4 2.334 CYP51A1 cytochrome P450, family 51, subfamily A, polypeptide 1 2.095 LIMS1 LIM and senescent cell antigen-like domains 1 2.091 YWHAE tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, epsilon polypeptide 2.042 OAS1 2′,5′-oligoadenylate synthetase 1, 40/46kDa 2.031 S100A11 S100 calcium binding protein A11 2.018 222378_at unknown transcribed sequences 0.496 SLC5A3 mitochondrial ribosomal protein S6 0.463 213089_at unknown transcribed sequences 0.406 PDE4B phosphodiesterase 4B, cAMP-specific 0.454 SVIL supervillin 0.386 RIPX rap2 interacting protein x 0.383

Expression of CD126 (IL-R alpha) on Plasma Cells in Monoclonal Gammopathies.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 5066-5066
Author(s):  
Syed T. Mahmood ◽  
Shaji Kumar ◽  
Teresa K. Kimlinger ◽  
Jessica L. Haug ◽  
Michael Timm ◽  
...  
Keyword(s):  
Plasma Cell ◽  
Monoclonal Gammopathy ◽  
Plasma Cells ◽  
Cell Subset ◽  
Primary Amyloidosis ◽  
Normal Plasma ◽  
Plasma Cell Disorders ◽  
Plasma Cell Disorder ◽  
Cell Disorder

Abstract Background: IL-6 is important for proliferation and inhibition of apoptosis in malignant plasma cells. Understanding the role of IL-6 receptor alpha chain (CD126) in the pathogenesis of plasma cell disorders may help in developing future treatment therapies for these diseases. A previous study has shown that CD126 (alpha subunit of IL-6 receptor) is expressed distinctly in myeloma, monoclonal gammopathy of unknown significance (MGUS), and plasmacytomas when compared to normal. We performed this study in order to confirm and describe the expression of CD126 in different plasma cell disorders. Design and Methods: Using flow cytometry we assessed CD126 expression on clonal plasma cells from patients with Primary Amyloidosis (n=7), monoclonal gammopathy of undetermined significance (MGUS) (n=13), smoldering Myeloma (SMM) (n=19) and active Myeloma (n=22), as well as normal plasma cells (n=9). Plasma cells were identified by their characteristic CD38/45 expression. The expression of CD126 was separately analyzed on the CD45 positive and negative plasma cells. CD 126 expression was considered significant when more than 20% of the cells had expression. Results: CD126 expression was seen distinctly in plasma cell disorder plasma cells and not in normal plasma cells when all plasma cells were studied together. The highest expression percentages were found in Amyloid (28%) followed closely by MGUS 29(%), then SMM (23%), and Myeloma (12%) cells. The CD45 neg subset was similarly positive in the plasma cell disorder group. In this group, MGUS showed the highest expression percentage followed distantly by Amyloid, Myeloma, and SMM. The CD45 pos subset was uniformly positive in expression of CD126. If was found that this subset expressed higher levels of CD126 in all the studied plasma cell disorders and normal plasma cells when compared to the CD45 neg subset. Conclusion: The findings of this study confirm the increased expression of CD126 in plasma cell disorders when compared to normal plasma cells. The higher expression of CD126 in the CD45 pos plasma cell subset has not been previously described. In addition, the CD45 pos subset expressed higher levels of CD126 in all study groups when compared to the CD45 pos subset. This data contributes to the understanding of IL-6 receptor physiology and confirms the important role of the CD45 pos subset in the proliferation of neoplastic plasma cells. The findings are in accordance with the increased proliferative rates seen in the CD45 fraction of malignant plasma cells.

Identification of New Upregulated Genes with Possible Relevance for Multiple Myeloma Tumorigenesis

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2707-2707
Author(s):  
Roberta Spetic Felix ◽  
Gisele W. B. Colleoni ◽  
Otavia L. Caballero ◽  
Manuella Sampaio Almeida ◽  
Valeria C.C. Andrade ◽  
...  
Keyword(s):  
Gene Expression ◽  
Multiple Myeloma ◽  
Differential Expression ◽  
Plasma Cells ◽  
Meta Analysis ◽  
Genomic Analysis ◽  
Transcript Abundance ◽  
New Genes ◽  
Normal Plasma ◽  
Upregulated Genes

Abstract Serial analysis of gene expression (SAGE) allows a comprehensive profiling of gene expression within a given tissue and also an assessment of transcript abundance. Objectives: We generated SAGE libraries from normal and neoplastic plasma cells to identify genes differentially expressed in multiple myeloma (MM). Material and Methods: Normal plasma cells were obtained from palatine tonsils and MM SAGE library was generated from bone marrow plasma cells of MM patients. Results: We obtained 29,918 SAGE tags from normal and 10,340 tags from tumor libraries. Computer-generated genomic analysis identified 46 upregulated genes in the MM library. Ten upregulated genes were selected for further investigation. Differential expression was validated by quantitative real-time PCR in purified plasma cells of 31 patients and three controls. P53CSV, DDX5, MAPKAPK2, RANBP2 were found to be upregulated in at least 50% of the MM cases tested. All of them were also found upregulated in MM when compared to normal plasma cells in a meta-analysis using ONCOMINE microarray database. Antibodies specific to DDX5, RANBP2 and MAPKAPK2 were used in a TMA containing 57 MM cases and confirmed the expression of these proteins in 74, 96, and 21% of the MM samples, respectively. Conclusions: Analysis of differential expression using SAGE could identify new genes important for myeloma tumorigenesis (P53CSV, DDX5, MAPKPK2 and RANBP2) and that could potentially be useful as therapeutic targets.

Differential Expression and Non-Redundant Functions of NF-κB Transcription Factor Subunits in Germinal Center (GC) B Cell Subpopulations

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 216-216 ◽  
Author(s):  
Nicole Heise ◽  
Nilushi De Silva ◽  
Amanda Carette ◽  
Giorgia Simonetti ◽  
Govind Bhagat ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
Differential Expression ◽  
Plasma Cell ◽  
Germinal Center ◽  
Plasma Cells ◽  
Nuclear Translocation ◽  
Cell Subpopulations

Abstract Abstract 216 The majority of B cell-derived neoplasms, including Hodgkin and Non-Hodgkin lymphoma and multiple myeloma (MM), arise from antigen-specific B cells that have undergone the germinal center (GC) reaction of T-dependent immune responses. Recent work has demonstrated that GC-derived tumors frequently harbor genetic mutations in nuclear factor-κB (NF-κB) signaling pathway components, resulting in the constitutive activation of NF-κB signaling, thus identifying NF-κB as a critical player in GC-lymphomagenesis. Moreover, there is evidence for a preferential activation of particular NF-κB transcription factor subunits in tumor subtypes. Despite extensive knowledge about the biology of NF-κB, its potential function in the physiology and development of GC B cells, the presumptive tumor precursor cells, is largely unresolved. The NF-κB signaling cascade comprises 5 different subunits, which occur as homo- and heterodimers and can be activated via two different routes, the canonical (classical) and the alternative (non-canonical/classical) NF-κB pathways. RELA, c-REL and p105/p50 represent the subunits of the canonical, while RELB and p100/p52 comprise those of the alternative pathway. It is known that there is no active NF-κB signaling in tonsillar GC centroblasts. Conversely, NF-κB activation was shown to occur in a subset of GC centrocytes. In this study, we demonstrate that each of the 5 NF-κB subunits exhibit nuclear translocation in centrocytes. Surprisingly, we observed that centrocytes expressing the plasma cell master regulator BLIMP1 showed strong immunofluorescence (IF) staining for the alternative NF-κB subunit p100/p52 and weak expression of the canonical subunits p105/p50 and c-REL compared to surrounding lymphocytes. Plasma cells localized in the tonsillar subepithelium showed the same pattern of expression. This observed differential expression of alternative vs. canonical NF-κB subunits in plasma cells and B cells, respectively, is supported by gene expression profiling data of human B cell subpopulations. Moreover, we observed that a mouse lymphoma cell line (M12) shows activation of the alternative NF-κB pathway upon induction of plasma cell differentiation. Also, Western and IF analysis of MM vs. diffuse large B cell lymphoma (DLBCL) cell lines revealed high protein levels and nuclear translocation of both p52 and RELB and low levels and cytosolic localization of c-REL in MM cell lines, while the opposite pattern was observed in the analyzed DLBCL lines. In summary, the elevated protein expression and presumed activity of the alternative over the canonical NF-κB pathway in plasma cells and their precursors suggests that activation of the alternative NF-κB pathway in centrocytes may contribute to plasma cell development and/or physiology. To elucidate the in vivo function of individual NF-κB transcription factor subunits, we started by determining the extent to which deletion of c-REL specifically in GC B cells affects the biology and differentiation of GC and post-GC B cells. We generated and then crossed a conditional loxP-flanked rel (c-REL) allele to mice that express the Cre-recombinase in GC B cells instructed to undergo class switch recombination (Cγ1-Cre mice). Following immunization with a T-dependent antigen, PNA+CD95+ GC B cell numbers were markedly reduced in immunized relfl/flCγ1-Cre mice compared to rel+/+Cγ1-Cre control mice. In addition, immunohistochemical analysis of spleen sections for BCL6 and IgG1 showed significantly smaller GCs, and a strong reduction in the numbers of GC-derived IgG1-secreting plasma cells, in relfl/flCγ1-Cre mice compared to controls. Consistent with these findings, we observed that relfl/flCγ1-Cre mice showed dramatically reduced numbers of nitrophenyl (NP) hapten-specific cells 14 days after immunization with NP-KLH compared to the control mice. Taken together, these findings suggest that c-REL may be required for the maintenance of GC B cells or for their selection into the post-GC compartment. Of note, the results demonstrate that deletion of a single NF-κB subunit in GC B cells can have drastic effects, suggesting a lack of general redundancy of the canonical subunits during the GC reaction. These findings imply that c-REL activation needs to be tightly controlled during GC B cell development, and raise the possibility that other NF-κB subunits may also exert unique functions in GC B cell differentiation. Disclosures: No relevant conflicts of interest to declare.

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