Tear levels of interferon-gamma, interleukin (IL)-2, IL-4 and IL-5 in patients with vernal keratoconjunctivitis, atopic keratoconjunctivitis and allergic conjunctivitis

Background A predominance of TH2 activity in chronic allergic diseases, suc h as vernal keratoconjunctivitis (VKC) and atopic keratoconjunctivitis (AKC ), has been suggested recently. However, there is no published study on tea r levels of cytokines of the two different subgroups, TH1 and TH2, in patie nts with ocular allergy. Objectives We measured interferon (IFN)-gamma, interleukin (IL)-2, IL-4 and IL-5 levels in tears by ELISA, to determine whether the levels of these cy tokines are elevated in allergic ocular diseases when compared among patien t groups and normal controls. Methods Tear levels of IL-2, IFN gamma, IL-4 and IL-5 were measured by ELIS A using samples from patients with VKC, AKC (AKC-NP, without proliferative lesions; and AKC-P, with proliferative lesions), allergic conjunctivitis (A C) and normal subjects. The levels of these cytokines in tears and the clin ical severity of AD were also compared. Results Tear IL-4 level in patients with AKC was significantly higher than those in VKC, AC and controls, and tear IL-4 levels in patients with AKC-P vs VKC differed significantly. Tear IL-5 levels in patients with diseases a ssociated with proliferative lesions, VKC and AKC-P, were higher than those in AC and normal controls. However, tear level of IL-5 in patients with AK C-P was significantly higher than that in AKC-NP. Although the dermatologic al severity of AD correlated significantly with tear IL-4 level, IFN gamma, IL-2 and IL-5 levels did not correlate with dermatological severity of AD. Conclusion These results indicate that the TH2-like cytokines play an impor tant pathophysiological role in severe ocular allergic conditions such as A KC and VKC and that tear level of IL-5 may be a candidate marker to evaluat e the clinical status of ocular allergy. The different patterns of tear lev els of IL-4 and IL-5 among ocular allergic diseases may reflect the origin and immunological basis of these cytokines.