We report a method for introducing a glutamine synthetase (GS) selectable marker into myeloma cells in which transfectants are selected by growth in a glutamine-free medium. Vector amplification can subsequently be selected using the specific inhibitor of GS, methionine sulphoximine (MSX). Using this system, DNA sequences encoding a chimeric B72.3 IgG4 antibody were expressed from hCMV-MIE promoters in NSO myeloma cells. A cell line was isolated after a single round of selection for vector amplification which contains approximately 4 copies of the vector, secretes 10-15 pg/cell/day cB72.3 antibody during exponential growth and can accumulate 560 mg/l antibody in a fed-batch air-lift fermentation system. Productivity is stable in the absence of MSX selection.

Antibody fragments can be isolated rapidly using techniques such as phage display and can be expressed to high levels in microbial systems. However, to date such antibody fragments have been of limited use for many therapeutic applications because they are rapidly cleared from the body. We present a strategy for the site-specific chemical modification of antibody fragments with polyethylene glycol, which results in the production of antibody fragments with long in vivo half-lives and full retention of antigen-binding properties. This technology should allow more rapid and economical production of therapeutic antibodies for chronic disease therapy.

No abstract

No abstract

A novel approach has been developed for the isolation and maturation of human antibodies that replicates key features of the adaptive immune system by coupling in vitro somatic hypermutation (SHM) with mammalian cell display. SHM is dependent on the action of the B cell specific enzyme, activation-induced cytidine deaminase (AID), and can be replicated in non-B cells through expression of recombinant AID. A library of human antibodies, based on germline V-gene segments with recombined human D J regions was used to isolate low-affinity antibodies to human β nerve growth factor (hβNGF). These antibodies, initially naïve to SHM, were subjected to AID-directed SHM in vitro and selected using the same mammalian cell display system, as illustrated by the maturation of one of the antibodies to low pM K D . This approach overcomes many of the previous limitations of mammalian cell display, enabling direct selection and maturation of antibodies as full-length, glycosylated IgGs. affinity maturation | mammalian display