The enzymatic and protein-chemical properties of a biliary plasminogen activator, bilokinase (BK) were described by Oshiba and Ariga (JBC, 258, 622, 1983). In the present investigation, the immunological natures of BK were examined and compared with those of urokinase (UK). The tissue localizations of BK in hepato-biliary and other systems were studied using the immunofluorescent technique.
A precipitin line was clearly formed between BK and its anti-body whereas, no precipitin line formed between BK and UK-antibody, or between UK and BK-antibody.
The bovine BK-antibody inhibited bovine BK, but did not inhibit UK. On the contrary, the bovine UK-antibody inhibited bovine UK, but not bovine BK.
Bovine liver treated with bovine BK-antibody showed immunofluorescence in hepatic cells. Note that there are stained cells and unstained cells.
The following conclusions were obtained;—
1) BK and UK were immunologically distinct.
2) The localization of BK-antigen was clearly demonstrated in hepatic cells and in the mucosa of gall bladder with the immunofluorescent technique.
3) The presence of BK-antigen was also detectable in the outer and inner layers of blood vessels.
4) The site of BK production and the difference between BK and tissue plasminogen activators remain to be clarified.
