Functional expression of chimeric Fab of an anti-CD40L mAb: Vector design and culture condition optimization

CD40L is an important costimulatory molecule in the induction of the humoral and cell-mediated immune responses. 4F1, a specific murine antagonistic monoclonal antibody against human CD40L molecule, is a promising candidate biomedicine for autoimmune diseases, transplantation rejection and anti-angiogenesis therapy of cancer. To avoid the mAb induced thromboembolism as a consequence of platelet surface FcγR activation, we attempted to construct a chimeric Fab of 4F1 to minimize its side effects for potential clinical use. A chimeric version of anti-CD40L Fab was generated by transferring mouse variable regions into a human framework. Our study indicated that 4F1 could be simply and rapidly converted to chimeric Fab which could be expressed in bacteria and purified in reasonable quantities. This chimeric antibody maintained its bioreactivity to human CD40L.