In vitro phagocytosis assay

For in vitro phagocytosis assay, macrophages were plated at 5 × 10⁴ per well in a 24-well plate. Bovine serum albumin was labeled with FITC. Macrophages were incubated in serum-free medium for 2 h before adding 1 μM FITC-labeled BSA. The indicated Ec-LDP-TF, LDP-TF or LDP protein (10 μM) was added and incubated for 2 h at 37 °C. Macrophages were repeatedly washed and subsequently imaged with an inverted microscope.

To quantitatively compare the effect on the phagocytosis affinity of macrophages by various fusion proteins, FITC-labeled BSA fluorescence was then determined by flow cytometry.