Tumour necrosis factor alpha (TNFα) in tears of atopic patients after conjunctival allergen challenge

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Abstract
Proinflammatory cytokines, such as TNFα are involved in the pathogenesis of allergic rhinitis and asthma. Our aim was to study the tear fluid TNFα levels in atopic patients before and after topical ocular allergen challenge. Thirteen patients were first challenged with topical allergen in the left eye and then dilution buffer in the right eye. Tear fluid samples were collected before the challenges and after 5, 30 and 60 min. Clinical symptoms were scored. Tear fluid TNFα concentrations were measured using a double-antibody radioimmunoassay. TNFα release rates were calculated using the tear fluid flow in the collection capillary as an estimate for the tear secretion rate. The mean baseline TNFα concentrations (ng/L) were 1310 (allergen-challenged eye) and 967 (control eye), and release rates (pg/min) 1.81 (allergen-challenged eye) and 1.39 (control eye), respectively. In the allergen-challenged eye, TNFα concentrations and release rates were 1479 and 4.30 (5 min), 1367 and 3.20 (30 min) and 1426 and 3.80 (60 min). In the control eye, TNFα concentrations and release rates were 746 and 0.67 (5 min), 1001 and 0.92 (30 min) and 1504 and 1.05 (60 min). The release rates of the allergen-challenged eye were significantly increased at all time points after the challenge when compared with the baseline or the control eye. Increased TNFα release rates suggest that this cytokine is an early mediator of allergy after conjunctival challenge.