Antibodies refer to the protein produced and secreted in the B cells that tend to bind with any substance that enters our body such as a pathogen. The function of the antibody is to bind at the site of a specific antigen or microorganism such as viruses or bacteria. Antibodies, or immunoglobins, are naturally produced at the arrival of a foreign particle and play a critical role in preparing the immune system for defense against diseases and infections.
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Antibodies are Y shaped molecules with each tip dedicated to connecting with a certain antigen. The type of binding between the antigen and antibodies has fascinated scientists for many years as it plays a crucial role in the field of immunology. There is a wide variety of applications of antibodies such as in the Biochip technology, diagnosis of disease, immunofluorescence, and enzyme-linked immunosorbent assays.
But a common doubt about antibodies arises in understanding the difference between monoclonal and polyclonal antibodies. Monoclonal and Polyclonal are the two-primary classification of antibodies and play an important role in the diagnostics and treatment of a certain condition. This distinction is also necessary for choosing the right type of antibody during experiments for the best results. So how are these antibodies different? Well, here are four major differentiations between the two antibodies.
1. Composition
Monoclonal antibodies are the product of identical B cells that are clones of a single parent cell. It indicates that the molecules have a monovalent affinity and tend to recognize only the same epitope of an antigen. Every antibody inside a polyclonal mixture is, in fact, a monoclonal antibody. The term monoclonal refers to the process that segregates the B-cell and fuses it with an immortal hybridoma cell to create several identical antibodies. |
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Polyclonal, on the other hand, represents a colony of antibodies that are products of different B cell clones. Hence they have polyvalency and can recognize multiple epitopes of antigens. Each antibody that forms the collection in a polyclonal recognizes a unique epitope of the antigen and binds to it.
2. Production
Tissue culture is the most common technique for producing monoclonal antibodies as it is difficult to segregate the desired molecules from a pool of antibodies using other techniques. The process of extraction begins by injecting the antigen of interest into an animal subject, such as a mouse. The antigen injection occurs several times until the body starts to develop an immune response to the microbe. Following this, the B-lymphocytes get isolated from the spleen of the animal and a fusing with the myeloma cell line happens. It creates an immortalized B-cell-myeloma hybridomas. These hybridomas are capable of multiplicating in tissue culture and generating antibodies. The entire set then goes through screening for the desired monoclonal antibody, which then gets separated. |
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In the case of polyclonal antibody production, the process is rather easier when compared to the tissue culture method. The process of production begins with injection immunogen into the animal subject. This initiates a primary response in the subject. This process is followed by secondary and tertiary immunization that signals the body to produce higher rates of antibodies acting against the particular antigen. After immunization, the antibody separation happens directly from the serum, which is blood with the clotting proteins, and the red blood cells removed from the subject. The serum also gets purified in some cases to separate the proteins of interest from the rest of the composition.
3. Diagnostics and Treatments
Monoclonal antibodies utilize immortal hybridoma cells and hence can produce large quantities of antibodies with high consistency and homogeneity. While the initial characterization requires expertise, once identified, the behavior is certainly predictable in these antibodies. Its ability to bind to a specific epitope of an antigen makes it a molecule of interest in several clinical studies where capturing multiple epitopes is possible with a higher degree of specificity.Monoclonal is the best choice for areas such as affinity purification. But these antibodies are not receptive to change in the epitope, such as due to polymorphism, and hence we can see a dramatic fall in affinity even with the slightest variations. Also monoclonal are highly specific, which means detection across a wide range of species becomes impossible with these molecules.
The ability of Monoclonal antibodies to target specific molecules helps discover surface components of a cell. This application encourages the approval of several antibodies for treating various ailments such as rheumatoid arthritis, asthma, cancer, and several other illnesses. It plays a huge role in drug rejection in organ transplant patients that prevents graft disease. These antibodies are also useful as vectors for delivering drugs to target cells.
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On the other hand, Polyclonal offers ease of production at a very low cost. They are consistent even over varying factors such as pH and buffer, and tend to show higher affinity even with a low level of expression from the target cell as they bind at multiple epitopes. Polyclonal is useful in environments where the experiments require you to adapt to changes in the antigen.
Polyclonal plays a huge role in unknown antigen detection. But their ability to bind with multiple epitopes enables them to amplify the signal in a microarray flow cytometry that enhances the chances of detection. One of the biggest disadvantages of polyclonal is batch variability, as they are produced from different animals each time.
The lack of specificity in polyclonal is a major reason behind its inability to benefit in cancer treatment. The antibodies also show a high degree of cross-reactivity, which is not favorable in such areas. There is research underway to utilize polyclonal as an immunosuppressant for transplant patients. The possibility of using the same to treat certain ailments is also under research.
4. Application
The various properties of the antibodies indicate their most potent uses.Monoclonal antibodies are useful for:
- Identifying a certain antigen based on binding abilities
- Quantifying protein expression such as in fluorescence-activated cell sorting experiments.
- Experiments to create an animal model while eliminating a certain type of cell
- Detecting variations in phosphorylation states
- Detecting variations in molecular conformation
- Cell staining with considerably less background
- Identifying and detecting any single member of a protein family
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Polyclonal is the best choice for:
- Detecting low levels of certain antigens present in a subject
- Identifying the target present in a series of solutions of varying pH and salt concentrations
- Detecting unknown and known antigens and their isoforms that have high antigen homology
- Identifying a native type of protein from multiple assay types
- Identifying and capturing as many antigens as possible for applications such as during immunoprecipitation
- Detecting denatured proteins
The nature of the antibody youuse depends upon the requirements of your experiment. You can begin by analyzing the properties of the antibodies and the similarity in the existing applications with your experiments to identify the most appropriate sample to work with.
