Specific for human transferrin complex between transferrin and soluble transferrin receptor (N-terminal domain, Kd=2.85 x 10-11 M). Can be used for detection of transferrin in serum by sandwich immunoassay, recommended pairs for transferrin detection by sandwich immunoassay (coating - conjugate): 8B9 - 11D3, 8B9 - 12A6; recommended pair for transferrin-transferrin receptor complex detection by sandwich ELISA (coating - conjugate): 23D10 (Hytest cat.No # 4Tr26) - 8B9