Antibodies

Primary Antibodies | Secondary Reagents and Isotype Controls | Antibodies by Application | Antibody Quality and Reproducibility | Antibody Protocols | Antibody Webinars | Featured Content | Antibody Additional Resources

Primary Antibodies, Secondary Antibodies, and Isotype Controls

R&D Systems brand offers a wide range of antibodies for the detection of cytokines, adhesion molecules, proteases, neurotrophic factors, stem cell factors, signal transduction molecules, and developmental proteins. Monoclonal and polyclonal primary antibodies are available conjugated to fluorescent or enzymatic labels or unconjugated. With over 400,000 antibody products validated in 50+ species and 25+ applications, our antibodies fit into almost all workflows. Complete your experimental design with secondary antibodies and isotype control antibodies.

The R&D Systems website is now also home to the full Novus Biologicals antibody portfolio, which specializes in a diverse range of niche targets.

Antibody Quality and Reproducibility

Every R&D Systems antibody we produce is carefully tested to ensure outstanding performance. Our commitment and approach to reagent quality and our 100% guarantee allows you to be confident in your results and help you generate publication-quality data.

Featured Content

Additional Resources

• Custom Reagents & Contract Services
• Products for Immunology Research
• Development of Validated Monoclonal Antibodies White Paper
• CD4+ T Cell Subsets
• Immune Cell Culture & Analysis Guide
• Antibody Product Custom Quote
• Custom Antibody Services
• Custom Reagents & Contract Services
• Immunohistochemistry Troubleshooting Guide

Antibodies: Frequently Asked Questions

1. What is an Antibody?

   Antibodies are large glycoproteins produced by the immune system to help defend the host against foreign invaders. They are Y-shaped proteins that are composed of two identical heavy and light polypeptide chains. One heavy and light chain associate via their N-termini, forming a domain that will bind to its antigen. An antigen is a substance that initiates an immune response. It is typically a protein, but may also be a carbohydrate, small molecule, or nucleotide. Each antibody will only recognize and bind to one specific epitope (i.e. site) on an antigen. This specific binding allows antibodies to be powerful research tools for the detection of a specific protein in an assay.

2. How are Antibodies Used in Life Science Research?

   An antibody is a Y-shaped protein that is secreted by B cells in the immune system and recognizes a specific epitope on a protein or molecule. Due to their highly specific nature, antibodies have become essential reagents for biomedical research as they allow researchers to detect targets of interest. Over the years, a variety of techniques and applications have been developed using antibodies. These include ELISA, Flow Cytometry, Immunohistochemistry (IHC), Immunocytochemistry (ICC), Western blotting, and more.

3. What is the difference between monoclonal and polyclonal antibodies?

   Monoclonal antibodies are a homogeneous population of antibodies that are produced by a single clone of plasma B cells. These antibodies recognize and bind to one epitope on the antigen. Polyclonal antibodies are a heterogeneous mixture of antibodies that is produced by a population of clones of plasma B cells. The antibodies recognize the same antigen but bind to different epitopes on the antigen.

4. What are recombinant monoclonal antibodies?

   Recombinant antibodies are monoclonal antibodies that are produced by molecular cloning techniques instead of hybridoma-based technologies. In other words, recombinant antibodies can be produced animal-free; genes for specific light chains and heavy chains are inserted into expression vectors, which are introduced into host cell lines. The host cells produce the antibodies, which can then be collected. Advantages of recombinant monoclonal antibodies include improved lot-to-lot consistency and reproducibility, ability to scale up to gram quantities, and opportunity for high-throughput, animal-free production.

5. How do you test for antibody specificity?

   R&D Systems testing processes use multiple approaches to evaluate antibody specificity. Depending on the antibody and intended application, these approaches may include, but are not limited to, knockout validation, biological validation, positive and negative controls, and recombinant protein family testing. When available, product-specific validation methods and supporting data are identified on the applicable product page. Our validation practices are informed by relevant scientific literature and evolving community recommendations, including those from the International Working Group for Antibody Validation (IWGAV), YCharOS, and initiatives such as the HLDA Workshops.

6. How do you test for antibody reproducibility?

   R&D Systems evaluates antibody reproducibility through application-specific testing conducted at multiple stages of antibody development, manufacturing, and product release. Testing strategies are selected based on the antibody and intended application and may include assessments of performance characteristics relevant to the specified use. When available, product-specific validation methods and supporting data are identified on the applicable product page.

7. What are secondary antibodies?

   A secondary antibody is an antibody directed against another immunoglobulin (antibody) molecule. They are used to aid in the detection, sorting, or purification of target antigens.

8. What is an isotype control?

   All immunoglobulins will bind non-specifically to cells expressing Fc receptors on their surface. Antibodies raised in mice, particularly of the IgG2a isotype, bind strongly to some human leukocytes. Isotype or negative controls are incorporated into flow cytometry (or occasionally IHC) protocols to assess the level of non-specific binding to Fc receptors on the target cell.

9. Does your company make custom antibodies?

   Yes, our expert scientists will work with you to deliver the antibody that meets all your required specifications. In tandem, an assigned project manager will ensure clear and constant communication throughout. We generate antibodies under controlled conditions with rigorous quality control testing to ensure high specificity and outstanding performance in the desired application(s).

   Learn more about our Custom Antibody Services.

10. Could you please provide information on how to find positive controls for your primary antibodies?

    The images on our datasheets will provide detailed information on potential positive control cells and/or tissues, which have been previously tested by the lab for antibody validation. Source data images can be provided upon request, if available. We also provide a Related Products table at the top of the datasheet, which will contain useful control information where available. In addition to these tools, we recommend checking tools such as Uniprot or Protein Atlas to determine tissues and cell lines that highly express your protein of interest.

11. What is the difference between cross adsorbed/normal/purified antibodies?

    Pre-adsorption (also referred to as cross-adsorption) is an extra step to increase the specificity of an antibody. Antibodies (for example, antibodies recognizing rabbit IgG light-chains) are passed through a matrix containing immobilized serum proteins from potentially cross-reactive species (for example, antibodies that recognize sheep and bovine light-chains). Only antibodies specific to rabbit IgG-light chains will pass through the column. Antibodies cross-reacting with sheep or bovine IgG light-chains will bind and stay adsorbed to the matrix. The result of the procedure is a more specific antibody, which is especially useful in IHC when cross-reactivity is feared. Purified antibodies have been purified by binding to protein A or protein G or by binding to the immunogen used to generate the antibody.

12. Why has this antibody been discontinued, and is there a way to obtain the discontinued stock?

    Occasionally, it becomes necessary to discontinue products from our catalog. This may occur for a variety of reasons, including limited commercial demand, disruptions in supply from external collaborators, or unforeseen manufacturing challenges. In rare instances, a product may be discontinued due to quality-related concerns.
    We understand that product discontinuations can be inconvenient and, whenever possible, we will recommend a suitable alternative. Once an antibody is listed as unavailable on our website, all remaining inventory has been depleted and no additional vials are available. Please contact our technical support team for assistance in finding alternative products.

13. Is your guarantee that you will refund the full price of the antibody if it doesn't work as specified still honored with this sample size?

    All our products are backed by our Guarantee for the applications and species listed on the datasheet. This guarantee applies to sample sizes.

14. Does your company honor this guarantee if the antibody is purchased through a vendor?

    All our products are backed by our Guarantee for the applications and species listed on the datasheet.