Natural Killer Cells (NK) in Vernal Keratocojunctivitis (VKC)

Abstract

Purpose: : Recent data suggest that NK cells are important regulators of the allergen–specific T cell response in asthma and allergic inflammation. In this study the presence of NK cells in the conjunctiva of patients affected by VKC was evaluated and compared to healthy subjects.

Methods: : Conjunctival biopsies obtained from 6 patients with active VKC and 6 healthy subjects, were processed by histology and immunohistochemistry to identify NK cells infiltrating the conjunctiva. Standard immunoperoxidase and confocal microscopy analysis were performed using anti human CD56 (DAKO, USA). For each biopsy, three randomly selected microscopic fields (X40) from at least three slides, were evaluated for the number of CD56+ cells. ANOVA test was used to compare the number of CD56+ cells in the conjunctiva of VKC and controls.

Results: : NK cells were detected in all the conjunctiva of patients with VKC and in 75% (4/6) of healthy subjects. Statistical analysis showed a significant (p<0.001) increase in the number of CD56+ cells infiltrating the conjunctiva of patients with VKC (54±36 cells x optic field) when compared to healthy subjects (5±3 cells x optic field).

Conclusions: : This study represents the first observation of the involvement of NK cells in ocular allergic diseases. The marked increase of NK cells in VKC patients suggests a potential role of NKs in regulating Th1/Th2 balance through secretion of specific cytokines, opening new potential therapeutic approach targeting on these cells.

Keywords: conjunctivitis • inflammation • conjunctiva