Inject a suitable mammal with the appropriate antigen. These are typically goats, rabbits and mice. Larger mammals are generally preferable, as using them allows researchers to collect a greater amount of serum.
Allow the B-lymphocytes in the test animal to produce immunoglobulin G (IgG) antibodies for the antigen. These antibodies come from multiple cell lines and are therefore called polyclonal antibodies.
Extract the antiserum from the test animal. The ideal methodology for producing polyclonal antibodies should produce antiserum with a high concentration of antibodies that are highly specific to the desired antigen.
Use adjuvants to improve a polyclonal antibody's immune response to an antigen. An adjuvant is an agent that stimulates an antibody's immune response without having a specific antigenic effect by itself. Common types of adjuvants include aluminum salts, oils and virosomes. The mechanism by which adjuvants works is not currently well understood.
Prepare the antigen. Antigens that are polypeptides with a molecular weight less than 10,000 and antigens that aren't proteins will generally be conjugated to form larger carrier proteins. Bovine serum albumin is a common carrier protein and poly-L-lysine is used successfully to deliver polypeptides. Liposomes are also common for delivering small peptides.