polyclonal

Polyclonal refers to antibody populations derived from more than one B-cell clone. Polyclonal antibodies are generated when an animal or human is exposed to an antigen, producing a mixture of antibodies that recognize multiple epitopes on that antigen.

Typically, serum from immunized animals (for example rabbits, goats, or horses) is collected and may be used directly or purified, such as by affinity chromatography using the antigen to enrich antigen-specific antibodies. Polyclonal antisera can also be produced by hyperimmunization and collected as immune serum.

Because they consist of diverse antibody species with varying affinities, polyclonal antibodies can recognize multiple distinct sites on an antigen. This breadth provides robustness to antigenic variation but can cause cross-reactivity with related proteins and greater batch-to-batch variability.

Polyclonal antibodies are widely used in research and diagnostics for applications such as immunoassays, western blotting, immunohistochemistry, and immunoprecipitation. Therapeutic polyclonal antisera, historically used for antivenoms and certain toxin exposures, have been largely supplanted by monoclonal approaches but remain in use in some contexts.

Monoclonal antibodies arise from a single B-cell clone, offering uniform specificity for one epitope but potentially reduced tolerance to antigenic variation. Polyclonal antibodies offer broader recognition and easier production but with greater variability between batches.

See also: monoclonal antibody, antisera, hybridoma, affinity chromatography.