The serine proteinase inhibitor antileukoproteinase specifically accumulates in normal but not in arthritic cartilage.
OBJECTIVE
To investigate whether the serine proteinase inhibitor antileukoproteinase (aLP) specifically accumulates in articular and extraarticular cartilage in normal and arthritic rats after intravenous (i.v.) injection.


METHODS
[123I] or [125I] radiolabeled aLP and a control protein of comparable size were injected iv into normal rats or rats with chronic, antigen induced arthritis (AIA). Joint accumulation of the 2 proteins was followed by scintigraphy and organ tissue radioactivity was assessed by autoradiography and well counter measurements. Immunoprecipitation of aLP from articular cartilage was also performed and the content of charged molecules in normal and arthritic cartilage determined using toluidine blue staining.


RESULTS
The accumulation of both radiolabeled aLP and control protein in the normal joint was clearly detectable by scintigraphy, with significant differences between the 2 proteins. In accordance with the scintigraphic data, direct tissue radioactivity measurements, immunoprecipitation, and autoradiography showed highly specific accumulation of radiolabeled aLP in articular and extraarticular cartilage of normal rats. The specific accumulation of aLP in articular cartilage was lost in rats with AIA in parallel with a loss of charged matrix molecules.


CONCLUSIONS
I.v. injected serine protease inhibitor aLP specifically accumulates in articular and extraarticular cartilage of normal rats. This physiological pathway of cartilage accumulation, lost in proteoglycan depleted arthritic cartilage, may serve to maintain the local balance between proteinase function and inhibition.
Burkhardt
H
H
Department of Internal Medicine III, University of Erlangen-Nuremberg, Germany.
Meyer
P
P
Buchner
E
E
Palombo-Kinne
E
E
Heinzel-Wieland
R
R
Becker
W
W
Wolf
F
F
Kalden
J R
JR
Kinne
R W
RW
D000818:Animals; D001168:Arthritis / Q000378:metabolism*; D002356:Cartilage / Q000378:metabolism*; D005260:Female; D007275:Injections, Intravenous; D007596:Joints / Q000378:metabolism; D053491:Proteinase Inhibitory Proteins, Secretory; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D011917:Rats, Inbred Lew; D015842:Serine Proteinase Inhibitors / Q000378:metabolism*
D053491:Proteinase Inhibitory Proteins, Secretory; D011506:Proteins; D015842:Serine Proteinase Inhibitors