FCRL 与 FCRL2

CD38 and ZAP-70 are both useful prognostic markers for B-cell chronic lymphocytic leukemia (CLL), but are variably discordant with IGHV mutation status. A total of 5 human Fc receptor–like molecules (FCRL1-5) have tyrosine-based immunoregulatory potential and are expressed by B-lineage subpopulations. To determine their prognostic potential in CLL, FCRL expression was compared with IGHV mutation status, CD38 and ZAP-70 expression, and clinical features from 107 patients. FCRL1, FCRL2, FCRL3, and FCRL5 were found at markedly higher levels on CLL cells bearing mutated IGHV genes than on unmutated CLL cells or CD19+ polyclonal B lymphocytes. Univariate comparisons found that similar to CD38 and ZAP-70, FCRL expression was strongly associated with IGHV mutation status; however, only FCRL2 maintained independent predictive value by multivariate logistic analysis. Strikingly, FCRL2 demonstrated 94.4% concordance with IGHV mutation compared with 76.6% for CD38 and 80.4% for ZAP-70. Compared with other indicators, FCRL2 was also superior at predicting the time to first therapy; the median treatment-free interval was 15.5 years for patients with high FCRL2 expression compared with 3.75 years for FCRL2-low patients. Our studies indicate that FCRL2 has robust predictive value for determining IGHV gene mutation status and clinical progression and thus may further improve prognostic definition in CLL.

… significantly refine the prognostic information provided by … FCRL2 expression was a significant independent prognostic … of FCRL2 expression is correlated with prognosis in B-CLL. …

Chronic lymphocytic leukemia (CLL) is the most pre-valent leukemia in Western countries and is characterized by a progressive accumulation of CD5 + monoclonal B cells in the blood and bone marrow. The clinical course in CLL is remarkably heterogeneous; the monoclonal population may expand in a protracted fashion over many years or increase rapidly, leading to bulky in fi ltration of lymphoid organs, progressive cellular and humoral immunode fi ciency, autoimmunity, and cytopenias 1,2 . Prognostication at the time of diagnosis has important implications for patient care and has been an active area of investigation over the past several decades. Various means of risk strati fi cation have been developed and validated, including clinical stage 3,4 , IGHV mutation status 5 , cytogenetic abnormalities 6 , and expression of surface proteins such as CD38 5,7 and CD49d 8 . Composite prognostic indices, such as the German CLL Study Group prognostic score and the CLL-IPI, have also been pro-posed 9,10 . Despite an abundance of validated prognostic indicators, decisions to initiate treatment are still based on the presence of symptoms and/or cytopenias, and there is no evidence yet that preemptive treatment based on adverse prognostic factors improves overall survival (OS). Therefore, the search for reliable and widely available indicators that can be easily assayed at diagnosis

B cell chronic lymphocytic leukemia (CLL) is a heterogeneous malignancy of two subtypes that can be stratified according to the mutation status of the immunoglobulin heavy chain variable region gene (IgVH). Because the clinical course of this disease differs dramatically between these subgroups, accurately identifying indolent patients (mutated-MT IgVH) from aggressive ones (unmutated-UM IgVH) is of increasing importance. CD38 and ZAP-70 expression are both considered useful prognostic markers in CLL and are utilized by most clinical laboratories. Although they are associated with Ig mutation status and predictive of clinical course, both proteins have some limitations and demonstrate variable discordance with IgVH mutation status. Thus, the proper diagnostic use of these indicators and their optimal detection remains under investigation. The identification of additional diagnostic and prognostic markers would not only be helpful for subgrouping CLL patients and choosing appropriate treatment options, but could also be informative for understanding the cellular origins and biological defects underlying this lymphoproliferative disorder. Recent characterization of five human Fc receptor-like (FCRL1–5) molecules possessing tyrosine-based activating and/or inhibitory potential that are expressed by distinct B cell subpopulations, suggests they could be useful diagnostic, prognostic and/or therapeutic markers in B lineage malignancies. To determine their prognostic potential in CLL, FCRL1–5 surface expression was evaluated with a panel of specific monoclonal antibodies by flow cytometry and compared with currently established markers of prognosis including IgVH mutation status, as well as CD38 surface expression, ZAP-70 cytoplasmic expression, and clinical parameters from 107 CLL cases. Our results demonstrate that FCRL1–3, and FCRL5 are expressed by CLL cells, but FCRL4 is not. Except for FCRL1, the expression of FCRL2, FCRL3, and FCRL5 was found at significantly higher levels on CLL cells than the polyclonal CD19+ B cell population in normal individuals. Univariate analysis revealed that all four FCRLs, as well as CD38 and ZAP-70, were significantly associated with IgVH mutation status. However multivariate logistical analysis confirmed that only FCRL2 and ZAP-70 maintain predictive value. Furthermore, significant negative correlations between FCRL2 and ZAP-70 expression (r=0.60, P<0.0001), and FCRL2 and CD38 expression (r=0.49, P<0.0001) were identified. Strikingly, FCRL2 provided excellent sensitivity and specificity, demonstrating 94.4% concordance with IgVH mutation compared to 77.6% for CD38 and 80.4% for ZAP-70. In a subset of patients for which clinical data were initially available, log-rank analysis revealed that similar to IgVH mutation status, FCRL2 can predict disease progression; the median time to first therapy was 13 years for FCRL2 high expressers compared to 4 years for FCRL2 low individuals. Our data indicate that FCRL2 is a novel prognostic marker of IgVH mutation status and clinical progression that may complement the clinical prognostic significance of CD38 and ZAP-70, and further improve therapeutic strategies for patients afflicted with CLL.

B cell chronic lymphocytic leukemia (CLL) can be stratified into indolent and aggressive subtypes according to the degree of somatic hypermutation evident in the immunoglobulin heavy chain variable region gene (IGHV). Despite some discordance with IGHV mutation status, both CD38 and ZAP-70 are routinely analyzed in clinical practice and are considered useful prognostic factors for segregating patients with aggressive-unmutated CLL (U-CLL). Members of the Fc receptor-like (FCRL1-5) family have immunoregulatory function and are preferentially expressed by B cells. Their distinct distribution pattern among subsets in healthy donors suggests that the FCRLs may also have useful diagnostic and/or therapeutic potential in B lineage malignancies. Previous work employing a receptor-specific monoclonal antibody (mAb-7F2) and an indirect staining method demonstrated that FCRL2 is particularly upregulated on the surface of indolent-mutated CLL (M-CLL) cells. Among 107 CLL samples, 52 U-CLL and 55 M-CLL, FCRL2 overlapped with IGHV status with 94.4% concordance, relative to 76.6% for CD38 (cutoff of 30%), and 80.4% for ZAP-70 according to the T/B ratio (cutoff of 4.0) or 74.8% by the % method (cutoff of 20%). Because several years have passed since our initial analysis using this reagent, we updated the clinical information to reassess the relationship among these prognostic parameters with FCRL2 staining and to further determine the usefulness of this biomarker in CLL. Similar to IGHV status [Hazard ratio (HR)=5.03], FCRL2 could also, but more powerfully, predict survival (HR=8.58). Both these features were superior to CD38 (HR=1.29) and ZAP-70 by either the T/B ratio (HR=1.42) or % (HR=1.04) approaches. The median survival for FCRL2 positive cases was 26.2 years and for FCRL2 negative donors was 12.7 years. With regard to disease progression, FCRL2 positive cases had a median treatment free interval of 13.5 years, whereas for FCRL2 negative donors it was only 3.2 years. Given these promising results, we pursued optimizing FCRL2 detection and assayability by flow cytometry to validate its clinical utility for diagnostic and prognostic purposes in CLL. A screen of FCRL2-specific mAbs led to the identification of a novel subclone termed 3E11, which by epitope mapping reacted with a site discrete from that of 7F2. The binding kinetics of these two mAbs also differed. According to surface plasmon resonance studies using an FCRL2-Fc recombinant protein, 3E11 possessed ∼2.5X better nanomolar affinity and a slower dissociation rate than 7F2. The superiority of 3E11 was also evidenced by its relatively stronger surface staining reactivity in flow cytometry analyses. To achieve a one-step staining strategy, 3E11 was directly conjugated with PE. Use of this PE-labeled reagent demonstrated brighter and more selective FCRL2 reactivity on M-CLL versus U-CLL (N=30) cells using either the post-Ficoll or whole blood-lysis preparation methods. Importantly, its reactivity was also stable over time (Concordance Correlation Coefficient of 0.9). As a promising CLL biomarker capable of selectively detecting the MT-CLL subtype and predicting disease progression and survival, the current findings demonstrate the practicability and reliability of a newfound mAb for validating the prognostic value of FCRL2 in CLL. Disclosures: LI: University of Alabama at Birmingham: Filed Patent, Filed Patent Patents & Royalties. Davis:NIH an University of Alabama at Birmingham: Patent Filed, Patent Filed Patents & Royalties, Research Funding.

… CLL samples with standard prognostic markers in CLL revealed that FCRL2 was highly expressed by MT-CLL … FCRL2 could predict IGHV status with 94.4% concordance, relative to 76.6…

… Our CLL case, displaying a … , FCRL2, and FCRL3, as well as the lack of FCRL5 expression and clinically presented a poor outcome. Due to the lack of concordance between FCRL2 …

… , FCRL2, FCRL3, and CD150) as additional potential markers with prognostic relevance in CLL. … of clinically characterized CLL cases; (ii) in combination with other prognostic markers in …

… (MFI) discriminated between CLL cells with mutated and unmutated IGHV … CLL, median time to first treatment was more than 4 times as long for patients whose cells expressed FCRL2 …

… of FCRL2 as a novel and potential prognostic biomarker in CLL. FCRL2 expression was also inversely associated with the clinical progression in B-CLL [Citation103]. We evaluated …

… that FCRL2 is a superior marker for stratifying MT-CLL and disease progression, which may complement and extend the prognostic … of FCRL2 as a standard diagnostic and prognostic …

… are critical for balancing B-cell response and function. Human Fc receptor like-2 (FCRL2), a member of the newly identified FCRL family, could influence B-cell signalling due to …

FcR-like (FCRL) 2 is a transmembrane protein with immunomodulatory potential that is preferentially expressed by memory B cells in humans. It has two consensus ITIMs in addition to a putative ITAM sequence in its cytoplasmic domain. We have confirmed the cellular distribution of FCRL2 and analyzed its functional potential to show that coligation with the BCR leads to tyrosine phosphorylation of its ITIM motifs and subsequent Src homology region 2 domain-containing phosphatase-1 recruitment to facilitate inhibition of BCR signaling. Mutational analysis indicates that the tyrosine residues in both inhibitory motifs of FCRL2 are required for complete inhibition of BCR signaling, whereas tyrosines in the putative activation motif are dispensable for signal modulation. These findings suggest a negative immunomodulatory function for FCRL2 in the regulation of memory B cells.

The Fc receptor‐like protein 2 (FCRL2) is a member of a family of receptors identified on the basis of sequence similarity with previously identified Fc receptors. The human FCRL2 transmembrane protein has 4 Ig‐like extracellular domains and a cytoplasmic tail containing one potential ITAM (immunoreceptor tyrosine‐based activation motif) and two ITIMs (immunoreceptor tyrosine‐based inhibitory motifs). To define its signaling potential in B cells, we constructed a chimeric receptor containing the extracellular and transmembrane domain of FcγRIIb fused to the intracellular domain of FCRL2 and expressed it in an Fc receptor deficient B cell line. Our functional analysis shows that, when coligated with the B cell receptor (BCR) by intact antibody, the FcγRIIb‐FCRL2 chimeric receptor is tyrosine phosphorylated, recruits the SHP‐1 phosphatase, and inhibits whole cell tyrosine phosphorylation. Preliminary data suggest that ERK activation and calcium mobilization are also inhibited upon crosslinking of FCRL2 with the BCR. These results indicate that FCRL2 may serve an inhibitory function in B cells. NIH/NIAID 5 T32 AI07051; 5 T32 GM08111‐20

… domain of FCRL4 contains three ITIM sequences. The cytoplasmic tails of FCRL2, 3, and 5 contain both ITAM and ITIM … This tissue distribution pattern of FCRL2 mRNA expression is …

… ITIM consensus sequences and defined the SH2 domain–containing phosphatase anchor protein (SPAP1/FCRL2… Davis) suggest high levels of FCRL2 expression on PCs in tonsils and …

… FCRL2 and FCRL5 contain two ITIMs and one ITAM-like sequence, whereas FCRL3 contains one ITIM … the cytoplasmic region of FCRL2, FCRL3, FCRL4 or FCRL5 is expressed and co-…

… We failed to demonstrate a lower protein expression of FCRL1, FCRL2 and CD22 in the different B-cell subsets by flow cytometry in patients with high neurodegeneration, although …

… and association of FCRL2 expression with inflammatory markers … mRNA in 82 patients, FCRL2 mRNA in 81 and FCRL4 … cells caused their homing and survival in the inflamed synovium. …

Background: It has been well-documented that the Fc receptor-like (FCRL) molecule contributes to the pathogenesis of certain autoimmune disorders. FCRL molecules belong to the immunoglobulin superfamily produced by B cells. Also, these molecules induce activating or inhibitory signals of B cells. According to this information and also considering the critical role of immune reactions in organ transplantation, the following experiment was performed to analyze the gene expression level of FCRLs in peripheral blood mononuclear cells of kidney transplant recipients. Materials and Methods: Blood samples were obtained from 32 renal transplant patients on days 1, 3, and 7 post-transplantations. Patients were divided into two groups according to the presence or absence of rejection. Also, 24 age-matched healthy subjects were enrolled as control group. After total RNA extraction from peripheral blood mononuclear cells (PBMC) and cDNA synthesis, the gene expression levels of FCRL1, FCRL2, and FCRL4 in each group were measured by real-time polymerase chain reaction. Results: Our results showed that FCRL1 expression levels in kidney transplant patients were significantly less than healthy controls. The overall FCRL2 expression level was not significantly different between them. However, at days 1 and 7, following transplantation in the non-rejected group FCRL2 level was significantly higher than the control group. Comparing the FCRL4 gene expression levels of both groups with healthy controls showed a significant decrease in the third and seventh days post-transplantation. Conclusion: It can be concluded that mononuclear cells, mainly B cells, have an essential role to play in kidney transplantation. [GMJ.2020;9:e1730]

We report cloning and characterization of FCRL2, a novel human gene that belongs … FCRL2 is expressed intracellularly in transfected 293T cells. Expression analysis revealed FCRL2 …

… to compare them with our results. Initial microarray studies have identified FCRL2 and 3 to be associated to the indolent disease.17 Comparison of flow cytometry results in a limited …

… , a supervised analysis using sam (Multiclass analysis) was carried out on 60 CLL samples … (Zinc finger and BTB domain containing 20) and FCRL2 (Fc receptor-like molecule 2) were …

… Univariate analyses demonstrated that FCRL expression was strongly associated with IGHV … , only FCRL2 maintained independent prognostic value in multivariate analysis. Notably, …