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Monoclonal antibodies versus polyclonal antisera , Monoclonal antibodies

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2026-11-04

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Monoclonal antibodies versus polyclonal antisera

Monoclonal antibodies

Monoclonal antibodies offer the advantage of a continuous supply of antibodies with the same characteristics, so once a good antibody is selected it can be used indefinitely. After immunisation and successful test bleeds, monoclonal antibodies are made by the fusion of mouse lymphocytes (or lymphocytes from other species) from the spleen with myeloma cells. The resultant hybridoma cells are separated by limiting dilution to give single cells that secrete single monoclonal antibodies. This technique was first described in 1975 and is now in routine use (Kohler and Milstein 1975). Monoclonal antibodies generally have lower affinity than polyclonal equivalents, which can lead to less-sensitive assays. Monoclonal anti bodies are not more specific than polyclonal antisera, but once a specific antibody is selected, the cell line can be stored and the antibody produced indefinitely. Note that in drug testing, it is possible for an antibody to be too specific, as it may be desirable to have broad cross-reactivity to a drug family (such as benzodiazepines) or to a single drug and its metabolites (such as buprenorphine). Monoclonal antibodies offer the advantages of purity and homology, which is useful for circumstances in which the antibody is being labelled or conjugated as part of the immunoassay set-up– for example when being labelled with an enzyme or coated with colloidal gold. Other molecular biology and recombinant techniques, such as phage display (Chiswell and McCafferty 1992), in which the genetic code is harnessed to produce antibodies, give an exciting additional source of this important immunoassay component.