FIGURE 1.

CD40 and TSHR are constitutively expressed by fibrocytes as determined by flow cytometry. We have previously reported that levels of fibrocytes are elevated in the peripheral blood from patients with thyroid-associated orbitopathy compared to controls.³⁷ Panel A demonstrates the three-step gating strategy for discriminating circulating fibrocytes among peripheral mononuclear cells. Fibrocytes are determined by forward and side scatter (step 1), then CD45 and collagen expression (step 2) and CD34 expression (step 3). Panel B demonstrates that fibrocytes constitutively express CD40 and TSHR (gray-filled histogram: isotype control; solid line: CD40 or TSHR). Mean fluorescent intensity of CD40 expression was 5.39 and 1.75, and of TSHR expression was 1.99 and 1.29, for cultured and circulating fibrocytes, respectively. The results are a representative example of three experiments.