© STEVE GRAEPELAntibodies are large proteins, weighing in at about 150 kDa. Four polypeptides—two heavy chains and two light chains—are linked by disulfide bonds to form a Y-shape molecule. The amino acid sequences at tips of the short ends of the Y vary greatly between antibodies produced by different B cells, while the rest of the molecule is relatively consistent. The variable portion of the antibody binds in a specific region (epitope) on a foreign protein (antigen) and signals the immune system to the presence of an invader.
To produce antibodies, researchers immunize lab animal with protein of interest. The animal’s B cells then generate antibodies that bind to different regions, or epitopes, on the protein. The diverse antibodies that bind to the target protein can then be isolated and purified for use. Because these bind numerous epitopes, they are called polyclonal antibodies.
© STEVE GRAEPEL
Alternatively, the immunized animals’ B cells can be isolated from the spleen or lymph nodes and fused with a tumor cell to generate immortal hybridoma lines. Those cell lines that produce the desired antibody against a specific epitope of the target protein can then be ...
