Antibodies (or immunoglobulins) are Y -shaped glycoproteins released by the immune system to detect and bind to "foreign" substances , known as " antigens ", triggering a cascade of actions to destroy these foreign invaders. Scientists would develop different antibodies for research use, which basically can be classified into primary and secondary antibodies . However, how to choose the right type of antibodies for different immunoassays in experiment procedures, such as western blotting (WB), enzyme-linked immunosorbent assays (ELISA), and immunoprecipitation (IP), is one of the most common questions for green hands in the laboratory. P rimary A ntibod y vs. Secondary Antibody Antibodies could be categorized into two types based on the binding capability and experimental applications— primary antibodies and secondary antibodies. The main difference between these two types of antibodies is that primary antibody binds specifically to ...