Purification and quantification of heavy-chain antibodies from the milk of bactrian camels.

Camel milk has a unique composition with naturally occurring heavy-chain antibodies (HCAbs), which exert rehabilitating potencies in infection and immunity. To characterize HCAb in camel milk, immunoglobulin G (IgG) was isolated from the milk of Camelus bactrianus by a combination of affinity chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis to purify and size-fractionate protein A and protein G, which were further identified by Western blotting, and were quantified by bicinchoninic acid (BCA) and ELISA. The results indicated that IgG1 fraction contains molecules of 50 kDa heavy chains and 36 kDa light chains. The HCAbs (IgG2 and IgG3 fractions) devoid of light chains, contain heavy chains of 45 kDa and 43 kDa, respectively, the amounts of which were significantly higher than that of the IgG1 in the milk of bactrian camels. Above all, we revealed the considerable amounts of HCAbs in the milk of bactrian camels, and developed a novel method for their purification and quantification. These findings provide the basis for developing potential effects of camel milk and its interface with the dairy industry, as well as future investigations of HCAb and its roles in human health and diseases.