In vitro antibodies: strategies for production and application.

The approaches to the production of antibodies (Ab) using the techniques of genetic engineering and expression are reviewed. Genetic engineering facilitates the production of proteins tailormade for an intended use. Bacterial and mammalian expression systems are commonly used for the production of Ab and Ab-like molecules. While genomic or cDNA cloning can be used to obtain the relevant variable regions, PCR-based cloning approaches facilitate the acquisition of additional binding specificities. Large numbers of different chimeric Abs with murine variable regions joined to constant regions from human and other species have been expressed and found to exhibit the expected binding specificities and effector functions. These molecules have been used to study the structural basis of effector functions such as complement activation and Fc receptor binding, and potentially they may be used as therapeutic agents. Carbohydrate has been shown to influence both variable and constant region function. Single-chain Abs and fusion proteins with Ab binding specificities joined to nonimmunoglobulin sequences provide a source of Ab-like molecules with novel properties, and genetically engineered Ab-like molecules provide a source of useful antigens. Combinatorial libraries produced in bacteriophage present an alternative to hybridomas for the production of Abs with desired combining specificities. Issues of the immunogenicity of the recombinant molecules are addressed.