Abstract
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 language | English |
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Journal | Molecular Imaging and Biology |
Volume | 17 |
Issue number | 1 |
Pages (from-to) | 87-93 |
Number of pages | 7 |
ISSN | 1536-1632 |
DOIs | |
Publication status | Published - Feb 2015 |