M. Akaiwa et al., Hakata antigen, a new member of the ficolin opsonin p35 family, is a novelhuman lectin secreted into bronchus alveolus and bile, J HIST CYTO, 47(6), 1999, pp. 777-785
Hakata antigen was first reported as a serum protein that reacted with an a
utoantibody from patients with systemic lupus erythematosus. Recently, it h
as been found that Hakata antigen is a new member of the ficolin/opsonin p3
5 family, which is a distinct lectin family, on the basis of homology of st
ructures and the common characteristic of possessing lectin activity. In th
is study we analyzed the tissue distribution of Hakata antigen. Hakata anti
gen mRNA and protein were generated in the lung and liver. In the lung, Hak
ata antigen was produced by both ciliated bronchial epithelial cells and Ty
pe II alveolar epithelial cells and was secreted into the bronchus and alve
olus. In the liver, Hakata antigen was produced by bile duct epithelial cel
ls and hepatocytes and was also secreted into the bile duct. These results
demonstrate that Hakata antigen is a unique lectin protein that exists not
only in serum but also in bronchus/alveolus and bile, and indicate that Hak
ata antigen plays a role in bronchus/alveolus and bile under physiological
conditions.