EasySep™ Human CD19 Positive Selection Kit

Immunomagnetic positive selection kit

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From: 635 USD


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Immunomagnetic positive selection kit
From: 635 USD

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The EasySep™ Human CD19 Positive Selection Kit is designed to isolate CD19+ cells from fresh or previously frozen peripheral blood mononuclear cells by positive selection. Desired cells are targeted with Tetrameric Antibody Complexes recognizing CD19 and dextran-coated magnetic particles. The cocktail also contains an antibody to human Fc receptor to minimize nonspecific binding. Labeled cells are separated using an EasySep™ magnet without the use of columns. Cells of interest remain in the tube while unwanted cells are poured off. The CD19 antigen is expressed on mature B cells and B cell progenitors but is lost upon maturation to plasma cells. It is also expressed on follicular dendritic cells.

For even faster cell isolations, we recommend the new EasySep™ Human CD19 Positive Selection Kit II (17854) which isolates cells in as little as 18 minutes.
• Fast and easy-to-use
• Up to 99% purity
• No columns required
  • EasySep™ Human CD19 Positive Selection Kit (Catalog #18054)
    • EasySep™ Human CD19 Positive Selection Cocktail, 1 mL
    • EasySep™ Magnetic Particles, 1 mL
  • RoboSep™ Human CD19 Positive Selection Kit with Filter Tips (Catalog #18054RF)
    • EasySep™ Human CD19 Positive Selection Cocktail, 1 mL
    • EasySep™ Magnetic Particles, 1 mL
    • RoboSep™ Buffer (Catalog #20104)
    • RoboSep™ Filter Tips (Catalog #20125)
Magnet Compatibility:
• EasySep™ Magnet (Catalog #18000)
• “The Big Easy” EasySep™ Magnet (Catalog #18001)
• RoboSep™-S (Catalog #21000)
Cell Isolation Kits
Cell Type:
B Cells
Sample Source:
Selection Method:
Cell Isolation
EasySep; RoboSep
Area of Interest:
Chimerism; Immunology

Technical Resources

Educational Materials


Frequently Asked Questions

Can EasySep™ be used for either positive or negative selection?

Yes. The EasySep™ kits use either a negative selection approach by targeting and removing unwanted cells or a positive selection approach targeting desired cells. Depletion kits are also available for the removal of cells with a specific undesired marker (e.g. GlyA).

How does the separation work?

Magnetic particles are crosslinked to cells using Tetrameric Antibody Complexes (TAC). When placed in the EasySep™ Magnet, labeled cells migrate to the wall of the tube. The unlabeled cells are then poured off into a separate fraction.

Which columns do I use?

The EasySep™ procedure is column-free. That's right - no columns!

How can I analyze the purity of my enriched sample?

The Product Information Sheet provided with each EasySep™ kit contains detailed staining information.

Can EasySep™ separations be automated?

Yes. RoboSep™, the fully automated cell separator, automates all EasySep™ labeling and cell separation steps.

Can EasySep™ be used to isolate rare cells?

Yes. We recommend a cell concentration of 2x108 cells/mL and a minimum working volume of 100 µL. Samples containing 2x107 cells or fewer should be suspended in 100 µL of buffer.

Are the EasySep™ magnetic particles FACS-compatible?

Yes, the EasySep™ particles are flow cytometry-compatible, as they are very uniform in size and about 5000X smaller than other commercially available magnetic beads used with column-free systems.

Can the EasySep™ magnetic particles be removed after enrichment?

No, but due to the small size of these particles, they will not interfere with downstream applications.

Can I alter the separation time in the magnet?

Yes; however, this may impact the kit's performance. The provided EasySep™ protocols have already been optimized to balance purity, recovery and time spent on the isolation.

For positive selection, can I perform more than 3 separations to increase purity?

Yes, the purity of targeted cells will increase with additional rounds of separations; however, cell recovery will decrease.

How does the binding of the EasySep™ magnetic particle affect the cells? is the function of positively selected cells altered by the bound particles?

Hundreds of publications have used cells selected with EasySep™ positive selection kits for functional studies. Our in-house experiments also confirm that selected cells are not functionally altered by the EasySep™ magnetic particles.

If particle binding is a key concern, we offer two options for negative selection. The EasySep™ negative selection kits can isolate untouched cells with comparable purities, while RosetteSep™ can isolate untouched cells directly from whole blood without using particles or magnets.
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Product Applications

This product is designed for use in the following research area(s) as part of the highlighted workflow stage(s). Explore these workflows to learn more about the other products we offer to support each research area.

Data and Publications


FACS Histogram Results with EasySep™ CD19+ Positive Selection Kit

Figure 1. FACS Histogram Results with EasySep™ CD19+ Positive Selection Kit

Starting with fresh peripheral blood mononuclear cells, the CD19+ cell content of the enriched fraction typically ranges from 97% - 99%.


Journal of immunology (Baltimore, Md. : 1950) 2011 MAY

CD1d and CD1c expression in human B cells is regulated by activation and retinoic acid receptor signaling.

Allan LL et al.


B cell activation and Ab production in response to protein Ags requires presentation of peptides for recruitment of T cell help. We and others have recently demonstrated that B cells can also acquire innate help by presenting lipid Ags via CD1d to NKT cells. Given the newfound contribution of NKT cells to humoral immunity, we sought to identify the pathways that regulate CD1 molecule expression in human B cells. We show that ex vivo, activated and memory B cells expressed lower levels of CD1d compared with resting, naive, and marginal zone-like B cells. In vitro, CD1d was downregulated by all forms of B cell activation, leaving a narrow temporal window in which B cells could activate NKT cells. CD1c expression and function also decreased following activation by CD40L alone, whereas activation via the BCR significantly upregulated CD1c, particularly on marginal zone-like B cells. We found that the CD40L-induced downregulation of CD1d and CD1c correlated with diminished expression of retinoic acid receptor $ (RAR$) response genes, an effect that was reversed by RAR$ agonists. However, BCR-induced upregulation of CD1c was independent of the RAR pathway. Our findings that both CD1d and CD1c are upregulated by RAR$ signaling in human B cells is distinct from effects reported in dendritic cells, in which CD1c is inversely downregulated. One functional consequence of CD1d upregulation by retinoic acid was NKT cell cytotoxicity toward B cells. These results are central to our understanding of how CD1-restricted T cells may control humoral immunity.
The Journal of experimental medicine 2011 JAN

Human B1 cells in umbilical cord and adult peripheral blood express the novel phenotype CD20+ CD27+ CD43+ CD70-.

Griffin DO et al.


B1 cells differ in many ways from conventional B cells, most prominently in the production of natural immunoglobulin, which is vitally important for protection against pathogens. B1 cells have also been implicated in the pathogenesis of autoimmune dyscrasias and malignant diseases. It has been impossible to accurately study B1 cells during health and illness because the nature of human B1 cells has not been successfully defined. This has produced controversy regarding the existence of human B1 cells. Here, we determined the phenotype of human B1 cells by testing sort-purified B cell fractions for three fundamental B1 cell functions based on mouse studies: spontaneous IgM secretion, efficient T cell stimulation, and tonic intracellular signaling. We found that a small population of CD20(+)CD27(+)CD43(+) cells present in both umbilical cord and adult peripheral blood fulfilled these criteria and expressed a skewed B cell receptor repertoire. These B cells express little or no surface CD69 and CD70, both of which are markedly up-regulated after activation of CD20(+)CD27(-)CD43(-) (naive) and CD20(+)CD27(+)CD43(-) (memory) B cells. This work identifies human B1 cells as CD20(+)CD27(+)CD43(+)CD70(-). We determined that the proportion of B1 cells declines with age, which may contribute to disease susceptibility. Identification of human B1 cells provides a foundation for future studies on the nature and role of these cells in human disease.
Blood 2010 MAY

IL-4 enhances IFN-lambda1 (IL-29) production by plasmacytoid DCs via monocyte secretion of IL-1Ra.

Megjugorac NJ et al.


The type-III interferon (IFN) family is composed of 3 molecules in humans: IFN-lambda1 (interleukin-29 [IL-29]), IFN-lambda2 (IL-28A), and IFN-lambda3 (IL-28B), each of which signals through the same receptor complex. Plasmacytoid dendritic cells (pDCs) are major IFN-lambda producers among peripheral lymphocytes. Recently, it has been shown that IFN-lambda1 exerts a powerful inhibitory effect over the T-helper 2 (Th2) response by antagonizing the effect of IL-4 on CD4(+) T cells and inhibiting the production of Th2-associated cytokines. Here, we asked whether Th2 cytokines exert reciprocal control over IFN-lambda production. IL-4 treatment during stimulation of human peripheral lymphocytes significantly elevated IFN-lambda1 transcription and secretion. However, pDCs were not directly responsive to IL-4. Using depletion and reconstitution experiments, we showed that IL-4-responsive monocytes are an intermediary cell, responding to IL-4 by elevating their secretion of IL-1 receptor antagonist (IL-Ra); this IL-1Ra acts on pDCs to elevate their IFN-lambda1 output. Thus, our experiments revealed a novel mechanism for regulation of both IFN-lambda1 production and pDC function, and suggests an expanded immunomodulatory role for Th2-associated cytokines.
Journal of acquired immune deficiency syndromes (1999) 2010 JUL

Pseudovirion particles bearing native HIV envelope trimers facilitate a novel method for generating human neutralizing monoclonal antibodies against HIV.

Hicar MD et al.


Monomeric HIV envelope vaccines fail to elicit broadly neutralizing antibodies or to protect against infection. Neutralizing antibodies against HIV bind to native functionally active Env trimers on the virion surface. Gag-Env pseudovirions recapitulate the native trimer and could serve as an effective epitope presentation platform for study of the neutralizing antibody response in HIV-infected individuals. To address if pseudovirions can recapitulate native HIV virion epitope structures, we carefully characterized these particles, concentrating on the antigenic structure of the coreceptor binding site. By blue native gel shift assays, Gag-Env pseudovirions were shown to contain native trimers that were competent for binding to neutralizing monoclonal antibodies. In enzyme-linked immunosorbent assay, pseudovirions exhibited increased binding of known CD4-induced antibodies after addition of CD4. Using flow cytometric analysis, fluorescently labeled pseudovirions specifically identified a subset of antigen-specific B cells in HIV-infected subjects. Interestingly, the sequence of one of these novel human antibodies, identified during cloning of single HIV-specific B cells and designated 2C6, exhibited homology to mAb 47e, a known anti-CD4-induced coreceptor binding site antibody. The secreted monoclonal antibody 2C6 did not bind monomeric gp120, but specifically bound envelope on pseudovirions. A recombinant form of the antibody 2C6 acted as a CD4-induced epitope-specific antibody in neutralization assays, yet did not bind monomeric gp120. These findings imply specificity against a quaternary epitope presented on the pseudovirion envelope spike. These data demonstrate that Gag-Env pseudovirions recapitulate CD4 and coreceptor binding pocket antigenic structures and can facilitate identification of B-cell clones that secrete neutralizing antibodies.
Journal of immunology (Baltimore, Md. : 1950) 2010 DEC

EBV latent membrane protein 1 is a negative regulator of TLR9.

Fathallah I et al.


EBV infects most of the human population and is associated with a number of human diseases including cancers. Moreover, evasion of the immune system and chronic infection is an essential step for EBV-associated diseases. In this paper, we show that EBV can alter the regulation and expression of TLRs, the key effector molecules of the innate immune response. EBV infection of human primary B cells resulted in the inhibition of TLR9 functionality. Stimulation of TLR9 on primary B cells led to the production of IL-6, TNF-$, and IgG, which was inhibited in cells infected with EBV. The virus exerts its inhibitory function by decreasing TLR9 mRNA and protein levels. This event was observed at early time points after EBV infection of primary cells, as well as in an immortalized lymphoblastoid cell line. We determined that the EBV oncoprotein latent membrane protein 1 (LMP1) is a strong inhibitor of TLR9 transcription. Overexpression of LMP1 in B cells reduced TLR9 promoter activity, mRNA, and protein levels. LMP1 mutants altered in activating the NF-$B pathway prevented TLR9 promoter deregulation. Blocking the NF-$B pathway recovered TLR9 promoter activity. Mutating the NF-$B cis element on the TLR9 promoter restored luciferase transcription in the presence of LMP1. Finally, deletion of the LMP1 gene in the EBV genome abolished the ability of the virus to induce TLR9 downregulation. Our study describes a mechanism used by EBV to suppress the host immune response by deregulating the TLR9 transcript through LMP1-mediated NF-$B activation.
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