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Product Description

The RA3.3A1/6.1 monoclonal antibody reacts with mouse B220 also known as CD45R. B220 is a 220 kDa transmembrane protein tyrosine phosphatase expressed on B cells and some subsets of T and NK cells. B220 plays a critical role in TCR and BCR signaling and is commonly used as a B cell marker. The RA3.3A1/6.1 antibody is commonly used for in vivo B cell depletion.

Specifications

Isotype Rat IgM
Recommended Isotype Control(s) InVivoMAb polyclonal rat IgG
Recommended Dilution Buffer InVivoPure pH 7.0 Dilution Buffer
Conjugation This product is unconjugated. Conjugation is available via our Antibody Conjugation Services.
Immunogen Mouse RAW 112 lymphosarcoma cells
Reported Applications in vivo B cell depletion
in vitro B cell negative selection
Formulation PBS, pH 7.0
Contains no stabilizers or preservatives
Endotoxin ≤1EU/mg (≤0.001EU/μg)
Determined by LAL assay
Purity ≥95%
Determined by SDS-PAGE
Sterility 0.2 µm filtration
Production Purified from cell culture supernatant in an animal-free facility
Purification Protein A
RRID AB_1107651
Storage The antibody solution should be stored at the stock concentration at 4°C. Do not freeze.
Need a Custom Formulation? See All Antibody Customization Options

Application References

  • in vivo B cell depletion
    Carmi, Y., et al (2015). "Allogeneic IgG combined with dendritic cell stimuli induce antitumour T-cell immunity" Nature 521(7550): 99-104.

    Whereas cancers grow within host tissues and evade host immunity through immune-editing and immunosuppression, tumours are rarely transmissible between individuals. Much like transplanted allogeneic organs, allogeneic tumours are reliably rejected by host T cells, even when the tumour and host share the same major histocompatibility complex alleles, the most potent determinants of transplant rejection. How such tumour-eradicating immunity is initiated remains unknown, although elucidating this process could provide the basis for inducing similar responses against naturally arising tumours. Here we find that allogeneic tumour rejection is initiated in mice by naturally occurring tumour-binding IgG antibodies, which enable dendritic cells (DCs) to internalize tumour antigens and subsequently activate tumour-reactive T cells. We exploited this mechanism to treat autologous and autochthonous tumours successfully. Either systemic administration of DCs loaded with allogeneic-IgG-coated tumour cells or intratumoral injection of allogeneic IgG in combination with DC stimuli induced potent T-cell-mediated antitumour immune responses, resulting in tumour eradication in mouse models of melanoma, pancreas, lung and breast cancer. Moreover, this strategy led to eradication of distant tumours and metastases, as well as the injected primary tumours. To assess the clinical relevance of these findings, we studied antibodies and cells from patients with lung cancer. T cells from these patients responded vigorously to autologous tumour antigens after culture with allogeneic-IgG-loaded DCs, recapitulating our findings in mice. These results reveal that tumour-binding allogeneic IgG can induce powerful antitumour immunity that can be exploited for cancer immunotherapy.

  • Becher, B., et al (2014). "High-dimensional analysis of the murine myeloid cell system" Nat Immunol 15(12): 1181-1189.

    Advances in cell-fate mapping have revealed the complexity in phenotype, ontogeny and tissue distribution of the mammalian myeloid system. To capture this phenotypic diversity, we developed a 38-antibody panel for mass cytometry and used dimensionality reduction with machine learning-aided cluster analysis to build a composite of murine (mouse) myeloid cells in the steady state across lymphoid and nonlymphoid tissues. In addition to identifying all previously described myeloid populations, higher-order analysis allowed objective delineation of otherwise ambiguous subsets, including monocyte-macrophage intermediates and an array of granulocyte variants. Using mice that cannot sense granulocyte macrophage-colony stimulating factor GM-CSF (Csf2rb(-/-)), which have discrete alterations in myeloid development, we confirmed differences in barrier tissue dendritic cells, lung macrophages and eosinophils. The methodology further identified variations in the monocyte and innate lymphoid cell compartment that were unexpected, which confirmed that this approach is a powerful tool for unambiguous and unbiased characterization of the myeloid system.

  • in vitro B cell negative selection
    Bouffi, C., et al (2015). "Transcription Factor Repertoire of Homeostatic Eosinophilopoiesis" J Immunol 195(6): 2683-2695.

    The production of mature eosinophils (Eos) is a tightly orchestrated process with the aim to sustain normal Eos levels in tissues while also maintaining low numbers of these complex and sensitive cells in the blood. To identify regulators of homeostatic eosinophilopoiesis in mice, we took a global approach to identify genome-wide transcriptome and epigenome changes that occur during homeostasis at critical developmental stages, including Eos-lineage commitment and lineage maturation. Our analyses revealed a markedly greater number of transcriptome alterations associated with Eos maturation (1199 genes) than with Eos-lineage commitment (490 genes), highlighting the greater transcriptional investment necessary for differentiation. Eos-lineage-committed progenitors (EoPs) were noted to express high levels of granule proteins and contain granules with an ultrastructure distinct from that of mature resting Eos. Our analyses also delineated a 976-gene Eos-lineage transcriptome that included a repertoire of 56 transcription factors, many of which have never previously been associated with Eos. EoPs and Eos, but not granulocyte-monocyte progenitors or neutrophils, expressed Helios and Aiolos, members of the Ikaros family of transcription factors, which regulate gene expression via modulation of chromatin structure and DNA accessibility. Epigenetic studies revealed a distinct distribution of active chromatin marks between genes induced with lineage commitment and genes induced with cell maturation during Eos development. In addition, Aiolos and Helios binding sites were significantly enriched in genes expressed by EoPs and Eos with active chromatin, highlighting a potential novel role for Helios and Aiolos in regulating gene expression during Eos development.

  • in vitro B cell negative selection
    Smyth, L. A., et al (2013). "Tolerogenic Donor-Derived Dendritic Cells Risk Sensitization In Vivo owing to Processing and Presentation by Recipient APCs" J Immunol 190(9): 4848-4860.

    Modification of allogeneic dendritic cells (DCs) through drug treatment results in DCs with in vitro hallmarks of tolerogenicity. Despite these observations, using murine MHC-mismatched skin and heart transplant models, donor-derived drug-modified DCs not only failed to induce tolerance but also accelerated graft rejection. The latter was inhibited by injecting the recipient with anti-CD8 Ab, which removed both CD8(+) T cells and CD8(+) DCs. The discrepancy between in vitro and in vivo data could be explained, partly, by the presentation of drug-modified donor DC MHC alloantigens by recipient APCs and activation of recipient T cells with indirect allospecificity, leading to the induction of alloantibodies. Furthermore, allogeneic MHC molecules expressed by drug-treated DCs were rapidly processed and presented in peptide form by recipient APCs in vivo within hours of DC injection. Using TCR-transgenic T cells, Ag presentation of injected OVA-pulsed DCs was detectable for in vivo. In support of this observation when mice lacking CD8(+) DCs were pretreated with drug-modified DCs prior to transplantation, skin graft rejection kinetics were similar to those in non-DC-treated controls. Of interest, when the same mice were treated with anti-CD40L blockade plus drug-modified DCs, skin graft survival was prolonged, suggesting endogenous DCs were responsible for T cell priming. Altogether, these findings highlight the risks and limitations of negative vaccination using alloantigen-bearing “tolerogenic” DCs.

Product Citations

  • Erythropoietin receptor on cDC1s dictates immune tolerance.

    In Nature on 1 February 2026 by Zhang, X., McGinnis, C. S., et al.

    PubMed

    Type 1 conventional dendritic cells (cDC1s) are unique in their efferocytosis1 and cross-presenting abilities2, resulting in antigen-specific T cell immunity3 or tolerance4-8. However, the mechanisms that underlie cDC1 tolerogenic function remain largely unknown. Here we show that the erythropoietin receptor (EPOR) acts as a critical switch that determines the tolerogenic function of cDC1s and the threshold of antigen-specific T cell responses. In total lymphoid irradiation-induced allograft tolerance9,10, cDC1s upregulate EPOR expression, and conditional knockout of EPOR in cDC1s diminishes antigen-specific induction and expansion of FOXP3+ regulatory T (Treg) cells, resulting in allograft rejection. Mechanistically, EPOR promotes efferocytosis-induced tolerogenic maturation7,11 of splenic cDC1s towards late-stage CCR7+ cDC1s characterized by increased expression of the integrin β8 gene12 (Itgb8), and conditional knockout of Itgb8 in cDC1s impairs tolerance induced by total lymphoid irradiation plus anti-thymocyte serum. Migratory cDC1s in peripheral lymph nodes preferentially express EPOR, and their FOXP3+ Treg cell-inducing capacity is enhanced by erythropoietin. Reciprocally, loss of EPOR enables immunogenic maturation of peripheral lymph node migratory and splenic CCR7+ cDC1s by upregulating genes involved in MHC class II- and class I-mediated antigen presentation, cross-presentation and costimulation. EPOR deficiency in cDC1s reduces tumour growth by enhancing anti-tumour T cell immunity, particularly increasing the generation of precursor exhausted tumour antigen-specific CD8+ T cells13 in tumour-draining lymph nodes and supporting their maintenance within tumours, while concurrently reducing intratumoural Treg cells. Targeting EPOR on cDC1s to induce or inhibit T cell immune tolerance could have potential for treating a variety of diseases.

  • Erythropoietin receptor on cDC1s dictates immune tolerance.

    In Nature on 1 February 2026 by Zhang, X., McGinnis, C. S., et al.

    PubMed

    Type 1 conventional dendritic cells (cDC1s) are unique in their efferocytosis1 and cross-presenting abilities2, resulting in antigen-specific T cell immunity3 or tolerance4-8. However, the mechanisms that underlie cDC1 tolerogenic function remain largely unknown. Here we show that the erythropoietin receptor (EPOR) acts as a critical switch that determines the tolerogenic function of cDC1s and the threshold of antigen-specific T cell responses. In total lymphoid irradiation-induced allograft tolerance9,10, cDC1s upregulate EPOR expression, and conditional knockout of EPOR in cDC1s diminishes antigen-specific induction and expansion of FOXP3+ regulatory T (Treg) cells, resulting in allograft rejection. Mechanistically, EPOR promotes efferocytosis-induced tolerogenic maturation7,11 of splenic cDC1s towards late-stage CCR7+ cDC1s characterized by increased expression of the integrin β8 gene12 (Itgb8), and conditional knockout of Itgb8 in cDC1s impairs tolerance induced by total lymphoid irradiation plus anti-thymocyte serum. Migratory cDC1s in peripheral lymph nodes preferentially express EPOR, and their FOXP3+ Treg cell-inducing capacity is enhanced by erythropoietin. Reciprocally, loss of EPOR enables immunogenic maturation of peripheral lymph node migratory and splenic CCR7+ cDC1s by upregulating genes involved in MHC class II- and class I-mediated antigen presentation, cross-presentation and costimulation. EPOR deficiency in cDC1s reduces tumour growth by enhancing anti-tumour T cell immunity, particularly increasing the generation of precursor exhausted tumour antigen-specific CD8+ T cells13 in tumour-draining lymph nodes and supporting their maintenance within tumours, while concurrently reducing intratumoural Treg cells. Targeting EPOR on cDC1s to induce or inhibit T cell immune tolerance could have potential for treating a variety of diseases.

  • Comparative Evaluation of Antibody-Oligonucleotide Conjugation Strategies for Multiplexed Imaging Applications.

    In Lab Invest on 1 January 2026 by Caraccio, C., van de Klashorst, J., et al.

    PubMed

    Antibody-oligonucleotide conjugates (AOCs) have emerged as versatile tools with applications spanning diagnostics, therapeutics, and high-dimensional imaging. One major application of these is in multiplexed imaging techniques, such as CO-Detection by indEXing, which allow for the visualization of tissue networks at the single-cell level. In this study, we evaluated 4 methods-maleimide-modified, amine-modified, dibenzocyclooctyne (DBCO)-modified, and a site-specific enzyme-based method-to optimize the generation of AOCs for multiplexed imaging applications. Our assessment focused on key performance parameters, including conjugation efficiency, signal brightness, stability, reproducibility, and cost-effectiveness. Each conjugation chemistry proved effective, though the azide chemistry with DBCO oligonucleotides demonstrated more consistent conjugation success and stable signal retention over time. Compared with other protocols, this method produced reliably bright images and offered a more favorable cost profile, as further confirmed in a full-scale CO-Detection by indEXing multiplexed imaging experiment that yielded reproducible spatial data. The observed stability and reproducibility of the DBCO approach suggest that it may help reduce reagent waste and labor costs while facilitating the development of more comprehensive antibody panels. These findings indicate that the DBCO-modified oligonucleotide conjugation method is a valuable option for generating AOCs for multiplexed imaging and target current shortcomings, enabling more consistent, broader, and deeper multiplexed profiling.

  • An epitope-directed mRNA vaccine inhibits tumor metastasis through the blockade of MICA/B α1/2 shedding.

    In Cell Rep Med on 18 March 2025 by Wang, R., Wu, J., et al.

    PubMed

    Antigenic peptide-based mRNA vaccines have been explored for immunotherapeutic use in various types of cancer because of their advantages in activating durable and specific immune responses. However, their role in modulating tumor metastasis is still unclear. Here, we identify a conserved linear epitope-based peptide, Ma3P, located in the proteolytic region of major histocompatibility complex (MHC) class I-related chain A (MICA) α3 and further design mCM10-L, an mRNA vaccine that encodes the carrier protein CRM197 and 10 tandem repeats of Ma3P. We demonstrate that vaccination with mCM10-L induces the production of specific antibodies that block MICA/B α1/2 shedding, activate CD8+ T cells and natural killer (NK) cells, and significantly inhibit MICA/B+ tumor metastasis in mice. Furthermore, mCM10-L stimulation triggers the production of specific antibodies to promote MICA/B-mediated immune killing in an in-vitro-interacting human organoid model and humanized mice. Our results indicate the potential clinical application prospects of the mCM10-L vaccine.

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