2.7 Immunofluorescence assay
The colon and spleen tissue slices were blocked with goat serum for 30 min in each group. The goat serum was discarded, and the sample was washed twice with PBS and wiped with water-absorbing paper. 50 µL of diluted antibody (1:500) was added to the sample, and PBS was added to the negative control group instead. After washing 3 times, fluorescent secondary (1:2000) was added, and the sample was incubated in the dark at room temperature for 2 hours. Washing twice with PBS, adding an antiquenching agent dropwise, the sample was observed, and images were acquired under a fluorescence microscope.