Aims: The essential roles of basophils as an initiator of chronic allergic reaction has been elucidated in mouse models. The aim of this present study was to analyze the in situ immunolocalization of basophils and other relevant inflammatory cells in chronic allergic keratoconjunctivitis.
Methods: Transmission electron microscopic (TEM) analysis was carried out to examine the existence of basophils in the giant papillae obtained from atopic keratoconjunctivitis (AKC) and vernal keratoconjunctivitis (VKC) patients. Cryostat sections of giant papillae were immunostained with basophil-specific antibody BB-1, and anti-CD4, anti-CD8, anti-CD20, anti-major basic protein (MBP), anti-IgE, and anti-FcϵRI-β antibodies.
Results: TEM analysis confirmed the existence of basophils in the giant papillae. Small clusters of basophils were observed in the substantia propria of giant papillae, especially at the vicinity of vascular endothelium and subepithelial regions. BB-1-positive basophil clusters were surrounded by T cells, B cells, IgE positive cells, and MBP-positive eosinophils. No BB-1-positive basophils were observed in the control conjunctivae.
Conclusion: Basophils may infiltrate from either vascular endothelium into the giant papillae. The existence of basophils at the center of inflammatory cells suggests the role of basophils as an initiator of chronic allergic conjunctivitis.