Recombinant expression of human mannan-binding lectin.

Mannan-binding lectin (MBL) constitutes an important part of the innate immune defence by effecting the deposition of complement on microbial surfaces. MBL deficiency is among the most common primary immunodeficiencies and is associated with recurrent infections and symptoms of poor immune complex clearance. Plasma-derived MBL has been used in reconstitution therapy but concerns over viral contamination and production capacity point to recombinant MBL (rMBL) as a future source of this protein for clinical use. Natural human MBL is an oligomer of up to 18 identical polypeptide chains. The synthesis of rMBL has been accomplished in several mammalian cell lines, however, the recombinant protein differed structurally from natural MBL. In this, study we compare rMBL produced in myeloma cells, Chinese hamster ovary (CHO) cells, human hepatocytes, and human embryonic kidney (HEK) cells. We report that rMBL structurally and functionally similar to natural MBL can be obtained through synthesis in the human embryonic kidney cells followed by selective carbohydrate affinity chromatography.