Optical imaging of experimental arthritis using allogeneic leukocytes labeled with a near-infrared fluorescent probe.
OBJECTIVE
The purpose of this study was to assess the feasibility of inflammation detection in an antigen-induced arthritis model using fluorescent leukocytes and optical imaging.


METHODS
Antigen-mediated monoarthritis was induced in the right knee of 12 Sprague-Dawley rats. Six rats remained untreated and six rats were treated with cortisone. All rats received ex vivo fluorescent-labeled rat leukocytes. Optical images of both knees were acquired before and at 5 min, 1 h, 4 h, and 24 h after cell injection. Images were evaluated qualitatively and quantitatively by calculating signal intensity ratios between the right arthritic (A) and contralateral normal (N) knee. A/N ratios were tested for significant differences between baseline values and values after cell injection using a paired t test as well as between the untreated and cortisone-treated group using an unpaired t test. Synovial specimens were processed and evaluated for labeled cells with fluorescence microscopy.


RESULTS
At 4 h and 24 h p.i., the A/N ratios of untreated arthritic knees showed a significant signal increase compared with baseline values (p<0.05) and a significant difference compared with A/N ratios of cortisone-treated animals (p<0.05). Fluorescent microscopy confirmed the presence of labeled cells in the arthritic synovium.


CONCLUSIONS
Inflammation in antigen-induced arthritis can be detected with ex vivo labeled allogenic leukocytes and optical imaging.
Simon
Gerhard H
GH
The Department of Radiology, S-372, UCSF Medical Center, University of California in San Francisco, 513 Parnassus Ave, San Francisco, CA 94143, USA. gerhardhsimon@hotmail.com
Daldrup-Link
Heike E
HE
Kau
Juli
J
Metz
Stephan
S
Schlegel
Juergen
J
Piontek
Guido
G
Saborowski
Olaf
O
Demos
Stavros
S
Duyster
Justus
J
Pichler
Bernd J
BJ
D000818:Animals; D001169:Arthritis, Experimental / Q000175:diagnosis* / Q000276:immunology / Q000473:pathology; D005260:Female; D005456:Fluorescent Dyes; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D007519:Isoantigens; D007962:Leukocytes / Q000276:immunology; D008856:Microscopy, Fluorescence / Q000379:methods; D055095:Optics and Photonics; D051381:Rats; D017207:Rats, Sprague-Dawley
D005456:Fluorescent Dyes; D007519:Isoantigens