ABSTRACT
Each rat immunoglobulin isotype has its specific physicochemical and biological properties. They have been described in Chapter 1. The treatments and use of monoclonal antibodies (MAbs) will be principally ruled by those properties. Knowing the immunoglobulin (Ig) isotype secreted by a hybridoma is therefore a necessity. Moreover, identifying them in culture supernatants is also a way to check the clonality of a culture and to select the desired clones. If more than one isotype is present in one supernatant, the culture generally has to be cloned again. However, some clones have been described to secrete two Ig isotypes, but this is extremely rare (Bazin and Libert, unpublished results).
