A new infrared fluorescent-labeling agent and labeled antibody for diagnosing microcancers.
OBJECTIVE
We have developed infrared fluorescent labeling agents and infrared-ray fluorescence endoscopes to establish a novel diagnostic technique. Since the fluorescence intensity of the initial labeled antibody (ICG-sulfo-OSu-labeled antibody) was not sufficient for practical use, we synthesized indocyanine green acylthiazolidinethione (ICG-ATT), which was expected to label various target molecules having amino groups efficiently.


METHODS
To confirm imaging of infrared fluorescence intensity of ICG-ATT- and ICG-sulfo-OSu-labeled anti-MUC1 antibodies, cotton thread was soaked in various concentrations of the antibody solution in 0.1M PBS, and observed under the epi-illumination infrared fluorescence microscope. Localization and the intensity of infrared fluorescence and DAB coloring was compared in paraffin sections of human gastric mucosa.


RESULTS
In the study of cotton threads, both labeled antibodies showed relatively clear infrared fluorescence, and significant difference was not observed between the two antibodies. ICG-ATT-labeled anti-MUC1 antibody produced stronger staining than that by ICG-sulfo-OSu-labeled antibody. Localization pattern of infrared fluorescent staining was in good agreement with that by the conventional method with oxidized DAB staining.


CONCLUSIONS
ICG-ATT is useful as a fluorescent-labeling agent for diagnosis of microcancers by infrared fluorescence endoscopes.
Tadatsu
Masaya
M
Department of Digestive and Cardiovascular Medicine, The University of Tokushima School of Medicine, 3-18-15 Kuramoto-cho, Tokushima City 770-8503, Japan.
Ito
Susumu
S
Muguruma
Naoki
N
Kusaka
Yoshihiro
Y
Inayama
Kumi
K
Bando
Terumi
T
Tadatsu
Yoko
Y
Okamoto
Koichi
K
Ii
Kunio
K
Nagao
Yoshimitsu
Y
Sano
Shigeki
S
Taue
Hiromi
H
D005753:Gastric Mucosa / Q000737:chemistry; D006801:Humans; D007208:Indocyanine Green / Q000032:analysis*; D008856:Microscopy, Fluorescence / Q000379:methods; D009369:Neoplasms / Q000175:diagnosis; D013055:Spectrophotometry, Infrared / Q000379:methods; D013194:Staining and Labeling / Q000379:methods*; D045162:Thiazolidinediones / Q000032:analysis*
D045162:Thiazolidinediones; D007208:Indocyanine Green