Definitions polyclonal antibodies

Polyclonal antibodies can react with many epitopes, whereas MAbs are restricted to one epitope on proteins that do not have repeating sequences.24 By definition, polyclonal immunoassays are generally much more sensitive but less specific than monoclonal assays. Bispecific or hybrid antibodies can be used to increase the affinity. Bispecific antibodies are formed by the fusion of two previously established hybridomas to produce antibodies displaying the binding characteristics of both of the antibodies in one molecule.25... 

In contrast, monoclonal antibodies consist of only one protein species and are produced by cell culture. Hence, monoclonal antibodies can be considered to be pure chemical compounds (to a first approximation). The respective clones (cell lines) can be cultured indefinitely and can be stored for quite a long time by freezing in liquid nitrogen. Unfortunately, the generation and production of monoclonal antibodies (Mabs) is much more difficult and expensive than that of polyclonal antibodies (Pabs). There is an important misunderstanding in this respect, which should be mentioned here. It is definitely not true that polyclonal antibodies are less selective or show lower afSnity than monoclonal ones. On the contrary, polyclonal antibodies often show a better performance than monoclonal... 

The definition of an association constant for an antibody—antigen reaction can become more complex if the antibody—antigen reaction iavolves a multivalent antigen, as is the case when a polyclonal antisemm is used for detection of an antigen. This type of multivalent binding is termed avidity and is defined by the equation ... 

The immunoglobulin fraction derived from the polyclonal hyperimmune serum of humans and animals has been used clinically in combating conditions such as bacterial infections and maternal immunization by Rh-positive cells from the fetus. Polyclonal sera raised against proteins have also been valuable diagnostic and research tools. However, the undefined composition of polyclonal antisera results in wide and unpredictable cross-reactivities. Furthermore, the quantities of antibody available are limited to the amount of serum an immunized animal can yield. Monoclonal antibodies described below circumvent these problems of definition and quantity associated with polyclonal sera. 

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