ICG administration did not activate immune cells in peripheral blood but can be observed in endosomes of macrophage cell cultures.

(A) Aggregated flow cytometry activation marker changes in participant peripheral blood samples taken across the study are shown measuring CD62L on T-cells (p = 0.914), (B) CD80 on monocytes (p = 0.914), and (C) CD62L on granulocytes (p = 0.698). Each point is a single blood sample from 7 subjects. All activation markers underwent validation with positive control stimuli. Human macrophage cell cultures developed visible signal within endosomes following 24 hours of culture with 0.2 mg/mL ICG by microscopy, which could be detected by flow cytometry in the near infrared channel. (D) Representative images shown for human cell cultures, with (green histogram) and without (grey histogram) ICG administration. Scale bars = 10 μm.