What is a hybridoma?

A hybridoma can be defined as a hybrid cell line capable of indefinitely producing antibodies under standard laboratory conditions. Compared to other antibody discovery methods, antibodies generated by hybridomas exhibit higher affinity, stability, and specificity.

How are hybridoma cells produced?

Hybridoma cell lines are produced by fusing plasma cells (which secrete highly affine antibodies) with compatible myeloma partners (malignant plasma cells, typically from the same organism). This process can be mediated by chemical or physical signals (e.g., electrical stimulation), leading to the immortalization of these high-yield, antibody-secreting cell lines.

How to Select Correctly Fused Hybridomas?

The fusion between plasma cells and their corresponding myeloma partners is not 100% efficient. Even under optimal conditions and with the most effective stimulation, cell fusion still yields a mixture of unfused and fused cells that require separation.

Since plasma cells have a short lifespan, they can be easily eliminated. However, removing unfused myeloma cells is more challenging. To improve the efficiency of the selection process, the myeloma partners used for fusion are deficient in HGPRT (hypoxanthine-guanine phosphoribosyltransferase), a key enzyme in the nucleotide salvage pathway. The cell mixture is then cultured in HAT medium (hypoxanthine-aminopterin-thymidine), where only cells containing HGPRT (hybridomas that inherit the enzyme from plasma cells) can survive.

How to Screen for Antibody Activity in Hybridoma Cell Lines?

In the initial stage, ELISA (enzyme-linked immunosorbent assay) can be used to screen hybridomas, as it is suitable for rapidly testing multiple samples. However, ELISA is not always the most suitable method for all applications. For example, therapeutic applications designed to target membrane-bound receptors may be better evaluated using alternative methods, such as flow cytometry, which can more accurately predict interactions with membrane proteins compared to ELISA. In contrast, for diagnostic applications, it is advisable to assess antibody performance in the intended assay format (e.g., ELISA, flow cytometry, Western blot, immunohistochemistry, etc.), as binding affinity may vary depending on sample type and specific detection conditions.

Why Are Positive Hybridomas Subcloned?

After identifying positive wells during the initial ELISA screening, hybridomas are transferred to larger volumes (e.g., a 24-well plate) in preparation for subcloning procedures. Subcloning of hybridomas is typically performed using the limiting dilution method to ensure the isolation of stable monoclonal populations. This method involves diluting the hybridoma culture and dispersing the cells into a 96-well plate to achieve monoclonality (one cell per well). To minimize the risk of generating mixed hybridoma populations, at least two rounds of limiting dilution should be performed.

What is the Ideal Antigen for Hybridoma Production?

Successful hybridoma generation primarily depends on the host's unique immune response. Therefore, the antigens used for immunization need to elicit a strong humoral response—in other words, they must be immunogenic. Not all antigenic substances (proteins, small molecules, lipids, carbohydrates, peptides) are inherently immunogenic. This capability depends on the degree of homology shared between the organism from which the antigen is derived and the host organism used for hybridoma production. The more evolutionarily distant the two organisms are, the greater the chance the host will mount an effective immune response against the target.

The most commonly used antigens include cells, proteins, peptides, and DNA. Proteins and peptides are the most popular choices because they allow for more precise targeting. By using proteins, it is possible to direct the antibodies produced by hybridomas to specific regions of a pathogen or protein complex. Additionally, peptides can be used to design hybridomas that target specific epitopes or a limited number of distinct epitopes. However, since most peptides lack sufficient immunogenicity, they are often conjugated to a carrier (adjuvant) to ensure the host organism recognizes them as foreign.

DNA immunization and cell-based immunization (using recombinant cells expressing the antigen on their surface) are preferred methods for handling unstable or complex antigens, such as G protein-coupled receptors (GPCRs) and other membrane-bound proteins. DNA immunization can also be employed when the antigen carries specific post-translational modifications that are critical for antibody activity.

In summary, selecting the right antigen depends not only on its native structure and source but also on the immune system of the host used for hybridoma production.

How do hybridomas produce monoclonal antibodies?

Hybridomas are the product of immortalized plasma cells that have previously undergone activation (via antigens) and affinity maturation (via recombination). Therefore, these cell lines represent the most advanced stage of B-cell development. These hybridomas produce high-affinity monoclonal antibodies (e.g., IgG or IgA in murine hybridomas) and secrete them into the culture medium. If the growth medium is serum-free (containing only trace amounts of nonspecific antibodies), the target antibodies can be easily extracted through direct purification using protein A, G, or L immobilized resins.

What are the benefits and limitations of using hybridoma technology for antibody discovery?

Hybridoma technology was first developed in the 1970s by scientists George Köhler and Cesar Milstein at the MRC Laboratory of Molecular Biology in Cambridge. The advantages and limitations of hybridoma technology in antibody discovery are well-documented. These hybrid cell lines are highly regarded for their ability to produce antibodies with high affinity, stability, and specificity in a cost-effective manner. In contrast, compared to in vitro antibody generation techniques, the development of hybridomas and their corresponding myeloma fusion partners requires a significant amount of time.

Why do hybridomas produce antibodies with the highest binding affinity?

Hybridomas are derived from fully mature plasma cells (effector B cells). These cells are typically generated through a complex process called linked recognition. Antigens stimulate antibody production, but the actual process requires collaboration among multiple cell types, including antigen-presenting cells (APCs, essential for digesting complex foreign molecules), T cells (activated by APCs), and B cells (activated by T cells). When B and T cells recognize the same antigen (linked recognition), T cells release chemical signals that drive the processes of antibody affinity maturation and class switching (from IgM to IgG/IgA/IgE production), ultimately leading to the generation of high-affinity monoclonal antibodies.

Which hosts can be used for hybridoma production?

The hybridoma technology was initially developed in mice. Due to genetic proximity, this technology can be easily adapted to other rodents, such as rats or guinea pigs. When using mouse myeloma partners for cell fusion, these rodents can usually produce stable hybridomas.

What are the applications of antibodies produced by hybridomas?

Given that most hybridomas are derived from mice or other rodents, the antibodies they produce are typically murine IgG molecules. Murine antibodies have low homology with human antibodies. Therefore, prolonged use of these molecules may trigger the development of human anti-mouse antibody (HAMA) responses, leading to faster clearance from the body, reduced therapeutic efficacy, and sometimes adverse allergic reactions.

For this reason, murine antibodies must undergo humanization before being considered suitable for therapeutic applications. Although this method has a longer turnaround time compared to in vitro approaches, humanized antibodies derived from mouse hybridomas remain one of the most successful biotherapeutic agents.

In contrast, murine antibodies are well-suited for diagnostic applications. Due to the cost-effectiveness of mouse hybridoma technology and the ability of hybridomas to naturally produce small quantities of monoclonal antibodies (sufficient for most diagnostic uses), the vast majority of diagnostic antibodies are of murine origin.

Can a single hybridoma-produced antibody be used for all types of diagnostic applications?

Developing an antibody that performs well across many different applications—such as flow cytometry, ELISA, Western blotting, and immunohistochemistry—is highly challenging. The reason lies in the differences in assay conditions and sample preparation among these platforms. For example, Western blot applications require antibodies targeting linear epitopes (peptides) because all proteins from a given sample are denatured before antibody binding. In contrast, flow cytometry primarily uses liquid samples where antigens are expected to retain their native conformation, so the antibody must target exposed regions.

Sample composition can also affect the performance of a given antibody. For instance, certain tissues or biological fluids may contain abundant components that share conserved regions with the antigen of interest. As a result, some specific samples may promote off-target binding, leading to high background noise and often yielding inconclusive or erroneous results.

For this reason, all antibodies intended for diagnostic use should be properly validated under specific assay formats, conditions, sample types, and required sample preparation protocols.

How to culture hybridomas in vitro?

There are several methods for culturing hybridomas in vitro. Until recently, the ascites production method was the most common process. However, this approach requires the use of animals and often yields stocks containing traces of nonspecific antibodies and other animal-derived contaminants.

Our recommendation is to culture hybridomas in suspension. Most hybridoma cell lines can grow under standard laboratory conditions, and we believe this is a more humane method for antibody production. Our suggestion also aligns with the latest EU report, which discourages the use of animals in antibody production when viable alternatives exist (EURL ECVAM Recommendation on Non-Animal-Derived Antibodies, published in May 2020).

In line with this recommendation, hybridomas can be grown in suspension in the presence of serum (e.g., 8-10% FCS – fetal calf serum or similar agents), supplemented with glutamine (known to stimulate antibody production) and antibiotics (to reduce bacterial contamination). However, serum also contains traces of nonspecific antibodies and other animal-derived contaminants. To overcome this issue and produce higher-purity bulk material, hybridomas can be adapted to serum-free and chemically defined media.

KMD Bioscience utilizes well-established hybridoma technology to produce high-quality monoclonal antibody (mAb) products. By fusing antigen-immunized mouse B cells with our proprietary myeloma cells, we generate stable hybridoma cell lines capable of consistently producing target antibodies. These cell lines undergo meticulous screening and cloning to ensure the resulting monoclonal antibodies exhibit exceptional specificity, affinity, and purity.Our mAb products are widely applied in biomedical research, clinical diagnostics, vaccine development, and therapeutic antibody discovery, providing comprehensive support for customers throughout the entire process—from basic research to drug development. Additionally, KMD Bioscience offers antibody humanization services to meet the demands of clinical applications.With an advanced technology platform, stringent quality control systems, and a team of experienced professionals, we deliver reliable and efficient solutions to clients in both academic research and the biopharmaceutical industry.