Conventional antibodies are large, Y-shaped proteins naturally produced by plasma B-cells and composed of two identical light chains and two identical heavy chains, both containing variable and constant domains. Antibodies are designed by nature to bind specifically to antigen targets via the antigen binding region which contains complementarity-determining regions (CDRs).
Knowledge of the structure-function relationships of antibodies allows the provision of a number of derivatives for a multitude of applications. Variants of antibodies, antibody fragments, bispecific or multispecific antibodies, antibody fusion products are commonly designed and produced.
New antibody formats such as heavy-chain-only antibodies have also been developed. Compared with conventional antibodies, camelid heavy-chain-only antibodies consist of only two identical heavy chains (with variable and constant domains) and the antigen-binding region consists of a single variable domain with three CDRs.
In general, antibodies, i.e. conventional antibodies, recombinant antibody derivatives or new antibody formats can be defined by (but are not limited to):