ELEVATED LEVELS OF SUBSTANCE-P IN TEARS OF PATIENTS WITH ALLERGIC CONJUNCTIVITIS AND VERNAL KERATOCONJUNCTIVITIS

Background Recent studies have suggested that the nervous system may p articipate in inflammatory processes. Substance P (SP) acts as a chemi cal mediator as well as a neurotransmitter. Objective In order to clar ify the pathogenesis of ocular allergic diseases, we assessed the conc entration of SP in tears. Methods Using a highly sensitive and specifi c double-antibody enzyme immunoassay (EIA), we determined the SP conce ntration in tears of 10 patients with seasonal allergic conjunctivitis , 10 with atopic dermatitis without keratoconjunctivitis (AD), 13 with vernal keratoconjunctivitis (VKC) and 65 normal controls. Giemsa's st aining for brush cytology samples and histocytological study by immuno cytochemical staining of giant papillary conjunctival cells from VKC a nd normal controls was conducted. Results The mean SP level was low in the normal controls and AD, whereas patients with seasonal allergic c onjunctivitis and VKC showed significant elevation of SP (P < 0.01). B rush cytology samples showed conjunctival epithelial cells with lympho cytes, neutrophils and eosinophils that. were not seen in normal subje cts. Histocytological examination demonstrated SP positive cells in th e conjunctiva of patients with VKC, but not in normal controls. Conclu sion This study suggests that the Increased level of SP in tears may c ontribute to the pathogenesis and severity of ocular allergic diseases .