Immunohistochemical Analysis of FcεRI Signaling

The diseased tissue sections were dewaxed, incubated at room temperature for 5–10 min, washed with distilled water, and soaked in PBS for 5 min. Drops of primary antibody were added, and the tissue sections incubated overnight at 4 °C. The tissue was then washed three times with PBS, biotin-labeled secondary antibody was added after 5 min, and the tissue sections were incubated at 37 °C for 30 min^{19 (link)}. The tissue was again washed three times with PBS, DAB stained, rinsed with water, hematoxylin stained, mounted, and imaged under a microscope (Olympus CX41, Tokyo, Japan). Polyclonal Rabbit IgG (ab37415, Abcam) was selected for isotype control antibody, which immunohistochemically showed all negative in 4 LGBLEL patients. The primary antibodies used for the immunohistochemical staining of proteins related to FcεRI signaling pathway were spleen tyrosine kinase (SYK) (AF3314; Affinity Biosciences, Beijing, China), p38 (mitogen-activated protein kinase, MAPK) (AF4001; Affinity Biosciences), c-Jun N-terminal kinase (JNK) (AF3318; Affinity Biosciences), phosphoinositide 3-kinase (PI3K) (AF3241; Affinity Biosciences) and extracellular signal-regulated kinases (ERK) (AF1015; Affinity Biosciences).