Ig L-chain Shuffling for Affinity Maturation of Phage Library-derived Human Anti-human MCP-1 Antibody Blocking its Chemotactic Activity

Monocyte chemotactic protein-1 (MCP-1, CC-chemokine ligand 2; CCL2) is involved in the development of various forms of chronic inflammations. Employing the naive human single-chain Fv displaying phage library, we established seven MCP-1-specific scFvs. The MC8 and MC32 clones exhibited blocking activity for the MCP-1-induced chemotaxis of THP-1 cells, in spite of their monovalency. The analysis of V gene usage showed that all clones bore the identical Vh1 gene, IGHV1-24*01, with variable DJ joining sequences, while their Vl usage was relatively varied, suggesting the preferential contribution of the Vh gene. Based on these findings, to minimize the deteriorative influences on the MCP-1 specificity of MC32, we aimed to achieve the affinity maturation of MC32 using MC32 L-chain shuffling library and select MC32 variants. Most MC32 variants increased their affinity by reducing the koff value with no influence of the antigen specificity. MC32 variants #22 or #56 showed ~15-fold higher affinity than MC32, indicating that the L-chain shuffling library is useful if the Vh is dominantly involved in the determination of the antigen specificity.