Why do monoclonal antibodies outperform polyclonal antibodies in many assays?

In monoclonal antibody preparations, all antibodies are derived from a single clone of B cells and target different parts (epitopes) of the antigen, thus exhibiting identical specificity.    On the other hand, polyclonal antibodies originate from a diverse population of B cells and recognize multiple epitopes, increasing the risk of cross-reactivity with other antigens.    Additionally, monoclonal antibody preparations contain only the target, specific antibodies, whereas polyclonal antibodies, unless purified via antigen-affinity chromatography, also include a substantial proportion of antibodies with unspecified reactivity.   Since monoclonal antibodies are produced in vitro rather than being derived from the serum of immunized animals (as with polyclonal antibodies), they offer numerous advantages over polyclonal antibodies.    These benefits apply not only when used as standalone reagents but also as critical components in various types of antibody-based immunoassays.

Does KMD provide matched antibody pairs?

Sandwich-based assays, such as ELISA and ELISpot, rely on the use of two different monoclonal antibodies—one immobilized as the capture antibody and the other used as the detection antibody. Typically, the two antibodies target different epitopes on the antigen. All of our ELISpot, ELISA, and FluoroSpot assays are based on such matched antibody pairs. However, the same antibodies are also available as individual reagents, making them suitable for other assays based on the same principle.

KMD Bioscience also offers customized services for paired antibody development.

What does antibody cross-reactivity mean?

Antibody cross-reactivity refers to the reactivity of an antibody to antigens other than the immunogen. Cross-reactivity can be a potential issue, and testing antibodies against closely related proteins is an important step in demonstrating their specificity. However, cross-reactivity between species is often beneficial, as it may allow the same antibody to detect corresponding antigens in other species. Cross-reactivity is most likely to occur between phylogenetically closely related species. For example, many antibodies targeting human proteins exhibit significant cross-reactivity with their counterparts in non-human primates.

How to validate cross-reactivity across different species?

Cross-reactivity validation tests have been conducted by KMD Bioscience using ELISpot and/or ELISA assays.

Do you have fluorescently labeled antibodies for flow cytometry?

KMD Bioscience offers a select range of monoclonal antibodies conjugated with labels such as FITC and HRP for flow cytometry applications.

Is it important to understand the end-use application when considering antigen detection solutions?

Yes, it is crucial to consider which assay your antibody will be used for. Not all antibodies are suitable for all applications. Western Blot detects denatured proteins, while flow cytometry, sandwich ELISA, immunofluorescence (IF), and other functional assays require antibodies capable of recognizing proteins in their naturally folded conformation. A thorough understanding of your requirements—including antigen design, immunization strategy, screening approach, purification, and validation—is essential for developing effective antibodies.

What Are the Advantages of Peptide Antigens for Antibody Development?

Natural proteins can serve as excellent antigens and have traditionally been used to generate antibodies for various purposes. However, some proteins are not easily isolated in sufficient quantities for characterization. Only a small fraction of these potentially useful proteins have been isolated and characterized. This makes most natural proteins impractical as a means of antibody production.The most logical alternative is to generate antibodies against peptides derived from natural protein sequences. In some cases, antibodies targeting such peptides can be even more effective than those targeting natural proteins.

Peptide antigen production only requires the amino acid sequence. This is particularly useful in certain scenarios:

Protein has not yet been discovered, but its gene sequence has been identified.

Protein has been discovered, but its full sequence has not been completely determined.

There is an insufficient quantity of the protein available.

The protein cannot be successfully expressed using recombinant techniques.

Peptide antibodies exhibit enhanced specificity. This provides the following benefits:

Elimination or minimization of potential cross-reactivity between structurally homologous proteins.

Ability to generate antibodies targeting specific epitopes.

Capability to produce antibodies against proteins with post-translational modifications.

Effective differentiation between two or more isoforms of a protein.

Peptide-based affinity purification is convenient and cost-effective. This offers the following advantages:

Enables efficient and relatively inexpensive immunoaffinity purification.

Allows production of highly pure, monospecific antibodies targeting desired epitopes through cross-adsorption with similar peptides.

If we produce an antibody against a peptide with only one phospho-residue, can it still recognize the protein when both sites are phosphorylated?

Yes, a single phospho-peptide antibody can recognize the protein when both sites are phosphorylated. However, a dual phospho-peptide antibody can also recognize the protein when only one site is phosphorylated. Therefore, it is difficult (if not impossible) to develop an antibody that exclusively recognizes the protein only when both sites are phosphorylated, without binding when just one site is phosphorylated.

What is the difference between Protein A/G-purified antibodies and antigen affinity-purified antibodies? When I have mAbs or pAbs, which purification method should I choose?

In simple terms, affinity purification isolates peptide-specific antibodies, whereas Protein A/G (Protein A or Protein G) purification purifies total immunoglobulins (Igs) from serum. Therefore, Protein A/G-purified antibodies contain both antigen-specific antibodies and endogenous Igs from the host animal, which may not be specific to the antigen.

Typically, for mAb purification, since the antibody is produced by hybridomas (derived from a single B cell), the concentration of the specific antibody is very high, so Protein A/G purification is sufficient. For pAb purification, since the collected antiserum contains about 10% specific antibodies and approximately 90% total Igs in the serum, antigen affinity purification is recommended.