Carotid artery plaque uptake of C-PK11195 inversely correlates with circulating monocytes and classical CD14CD16 monocytes expressing HLA-DR.

Background: We explored the relation between blood concentrations of monocyte/lymphocyte subsets and carotid artery plaque macrophage content, measured by positron emission tomography (PET) with C-PK11195.

Methods And Results: In 9 patients with carotid plaques we performed C-PK11195-PET/computed tomography angiography imaging and measurement of absolute concentrations and frequencies of circulating monocytes and T-cell subsets. Plaque standardized uptake value (SUV) for C-PK11195 was negatively correlated with concentrations of total monocytes (r = -0.58, p = 0.05) and CD14CD16HLA-DR classical subset (r = -0.82, p = 0.005). These correlations hold true also in relation to plaque target to background ratio. No correlation was observed between plaque SUV and CD3T lymphocytes, CD4T lymphocytes nor with activated CD3CD4T cells expressing HLA-DR.

Conclusions: We first demonstrated a reduction in the absolute concentration of monocytes and particularly in classical monocytes expressing HLA-DR in the presence of an increased uptake of C-PK11195 in carotid plaques. The present work, despite being a pilot study comprising only a small number of subjects provides new insights in the search for specific cellular biomarkers with potential diagnostic and prognostic value in patients with a known carotid plaque.