Søren Kragh Moestrup

Biodistribution and PET Imaging of a Novel [(68)Ga]-Anti-CD163-Antibody Conjugate in Rats with Collagen-Induced Arthritis and in Controls

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PURPOSE: The hemoglobin scavenger receptor CD163 is exclusively expressed on monocytes and tissue macrophages, also at sites of inflammation. We examined whether gallium-68 (Ga-68)-labeled anti-CD163-antibody can detect the receptor in vivo.

PROCEDURES: We radiolabeled anti-CD163 antibody with Ga-68 and evaluated stability and binding specificity of the conjugate ([(68)Ga]ED2) in vitro. Furthermore, tracer biodistribution was assessed in vivo in healthy rats and rats with acute collagen-induced arthritis (CIA) by MicroPET and tissue analysis.

RESULTS: Radiosynthesis of [(68)Ga]ED2 antibody yielded a tracer with high-specific activity and radiochemical purity. [(68)Ga]ED2 bound specifically to CD163 in vitro. In rats, [(68)Ga]ED2 rapidly accumulated in macrophage-rich tissues. The arthritic paws exhibited a low but significant [(68)Ga]ED2 uptake. Interestingly, the systemic distribution was also changed in the sense that a significantly higher liver uptake and lower spleen uptake of [(68)Ga]ED2 was measured in CIA rats that accordingly showed a corresponding change in level of CD163 expression.

CONCLUSIONS: [(68)Ga]ED2 specifically binds CD163 in vitro and in vivo. Biodistribution studies in CIA rats suggest that this novel tool may have applications in studies of inflammatory diseases.

Original languageEnglish
JournalMolecular Imaging and Biology
Volume17
Issue1
Pages (from-to)87-93
Number of pages7
ISSN1536-1632
DOIs
Publication statusPublished - Feb 2015

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