Detection of experimental autoimmune myocarditis in rats by 111In monoclonal antibody specific for tenascin-C.
BACKGROUND
Although the identification of inflammatory infiltrates in endomyocardial biopsy specimens is necessary for the definite diagnosis of myocarditis, the biopsy test is invasive and is not sensitive. Therefore, a new diagnostic technique for the early and noninvasive evaluation of myocarditis has been awaited. Expression of tenascin-C (TNC), one of the oligometric extracellular glycoproteins, is induced in various pathological states, including inflammation, suggesting that TNC can be a molecular marker of myocarditis.


RESULTS
An 111In anti-TNC monoclonal antibody Fab' fragment was injected intravenously into rats with experimental autoimmune myocarditis (EAM), and the biodistribution of this radiotracer was measured. Rapid clearance of radioactivity from the blood was observed in both EAM and control rats (<1% at 6 hours after injection). Myocardial uptake of the tracer was much higher in EAM rats than in control rats (7.54-, 4.39-, and 3.51-fold at 6, 24, and 48 hours after injection, respectively). By autoradiography, high radioactivities were clearly observed in the regions indicative of inflammation in EAM rats. Single-photon emission CT imaging demonstrated the focal myocardial uptake of 111In anti-TNC Fab' in vivo.


CONCLUSIONS
Radiolabeled anti-TNC Fab' may be useful for the noninvasive diagnosis of myocarditis.
Sato
Mikio
M
Department of Cardiovascular Science and Medicine, Graduate School of Medicine, Chiba University, Chiba-shi, Chiba, Japan.
Toyozaki
Tetsuya
T
Odaka
Kenichi
K
Uehara
Tomoya
T
Arano
Yasushi
Y
Hasegawa
Hiroshi
H
Yoshida
Katsuya
K
Imanaka-Yoshida
Kyoko
K
Yoshida
Toshimichi
T
Hiroe
Michiaki
M
Tadokoro
Hiroyuki
H
Irie
Toshiaki
T
Tanada
Shuji
S
Komuro
Issei
I
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000493:pharmacokinetics*; D001327:Autoimmune Diseases / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D001345:Autoradiography; D015415:Biomarkers / Q000032:analysis; D005260:Female; D007140:Immunoglobulin Fab Fragments / Q000378:metabolism; D007205:Indium Radioisotopes; D009205:Myocarditis / Q000000981:diagnostic imaging / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D009206:Myocardium / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D019063:Tenascin / Q000276:immunology* / Q000378:metabolism; D015899:Tomography, Emission-Computed, Single-Photon
D000911:Antibodies, Monoclonal; D015415:Biomarkers; D007140:Immunoglobulin Fab Fragments; D007205:Indium Radioisotopes; D019063:Tenascin