What are antibodies?

Antibodies are proteins produced by the body’s immune system when it detects harmful substances, called antigens. Examples of antigens include microorganisms (such as bacteria, fungi, parasites and viruses) and chemicals.

Antibodies can be produced when the immune system mistakenly regards healthy tissue as a harmful substance. This is called an autoimmune disorder. Each type of antibody is unique and defends the body against a specific type of antigen.

Each antibody can bind to only one specific antigen. The purpose of this binding is to help destroy the antigen. Some antibodies destroy antigens directly. Others make it easier for white blood cells to destroy the antigen. An antibody is a type of immunoglobulin.

What is a primary antibody?

A primary antibody can be defined as an immunoglobulin that binds specifically to proteins. It is the antibody that binds directly to the antigen. This is achieved by recognition of an epitope present on the antigen by the variable region of the primary antibody. They are developed as polyclonal and monoclonal antibodies. These antibodies are useful for research purposes to detect biomarkers for diseases such as diabetes, cancer, Alzheimer’s disease and Parkinson’s disease. A fluorophore or enzyme is not present in this proteins.

What is a secondary antibodies?

Secondary antibodies bind to the heavy chains of primary antibodies to aid in the detection, sorting and purification of target antigens. Secondary antibodies do not interfere with the binding procedure of primary antibodies to antigens. They do not bind directly to the antigen. Once the primary antibodies bind directly to the target antigens, the secondary antibodies come and bind to this proteins. The secondary antibody must be specific for the antibody species and for the isotope of the primary antibody during antigen detection. The type of secondary antibody is selected by the primary antibody class, the host of origin, and the preferred marker. Most primary antibody classes are IgG class.

Structure of antibodies

The structure of all this proteins are very similar. On the one hand, they have a section called the “constant region” (Fc), which is the one that can bind to immune cell receptors, such as macrophages or mast cells s, and on the other hand they also have a “ variable part ” (Fab), which recognises the antigen.

This variable part is so called because it is specific for each antigen, depending on whether it is B Cell that produces it. This mechanism of variability allows the immune system to generate a large battery of this proteins, unique and specific to a given antigen, and thus initiate a response tailored to the pathogen.