Leukotriene C-4 (LTC4) is synthesized by binding Of glutathione to LTA(4), an epoxide derived from arachidonic acid, and further metabolized to LTD4 and LTE4 We previously prepared a monoclonal antibody with a high affinity and specificity to LTC4. To explore the Structure of the antigen-binding site of a monoclonal antibody against LTC4 (mAbLTC), we isolated full-length cDNAs for heavy and light chains of mAbLTC The heavy and light chains consisted of 461 and 238 amino acids including a signal peptide with molecular weights of 51,089 and 26,340, respectively An expression plasmid encoding a single-chain antibody comprising variable regions of mAbLTC heavy and light chains (scFvLTC) was Constructed and expressed in COS-7 cells The recombinant scFvLTC showed a high affinity with LTC4 comparable to mAbLTC The scFvLTC also bound to LTD4 and LTE4 with 48% and 17% reactivities, respectively, as compared with LTC4 binding, whereas the antibody showed almost no affinity for LTB4 (C) 2010 Elsevier Inc All rights reserved