Th1- and Th2-type cytokines in chronic ocular allergy.
BACKGROUND
Previous reports have suggested that Th2-type cytokines are important in the pathogenesis of ocular allergic diseases. The purpose of this study is to measure levels and mRNA expression of Th1- and Th2-type cytokines in patients with active vernal keratoconjunctivitis (VKC) and atopic keratoconjunctivitis (AKC).


METHODS
Tear samples and tear-isolated cells were obtained from 9 healthy participants (CT--controls), 28 VKC, and 6 AKC patients. IL-4, IL-13, and interferon gamma (IFNgamma) tear levels were determined by ELISA, and IL-4 and IFNgamma tear cell mRNA expression by RT-PCR. Effects of these cytokines on IL-6 and IL-8 secretion, and on ICAM-1 expression by conjunctival fibroblasts, were evaluated by ELISA and flow cytometry respectively.


RESULTS
Interleukin-4 tear levels were increased in VKC and AKC compared with CT, but only IFNgamma significantly correlated with corneal involvement. An IL-4/13-dominant profile was found in 50% of VKC and in 17% of AKC patients, while a IFNgamma-dominant profile was found in 18% of VKC and in 17% of AKC patients. IL-4 and IFNgamma transcripts were detected in tear cells from 11 out of 12 VKC patients. IFNgamma upregulated expression of ICAM-1 on conjunctival fibroblasts and the secretion of IL-6 and IL-8.


CONCLUSIONS
Although both IL-4 and IFNgamma are detected in tears, only IFNgamma levels correlated with disease severity and upregulated ICAM-1 on conjunctival fibroblasts, suggesting the role of IFNgamma in the inflammatory phase of chronic allergic eye diseases.
Leonardi
Andrea
A
Department of Neuroscience, Ophthalmology Unit, Via Giustiniani 2, 35128, Padova, Italy. andrea.leonardi@unipd.it
Fregona
Iva A
IA
Plebani
Mario
M
Secchi
Antonio G
AG
Calder
Virginia L
VL
D000293:Adolescent; D000328:Adult; D018929:Cell Culture Techniques; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease; D003233:Conjunctivitis, Allergic / Q000235:genetics / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D007371:Interferon-gamma / Q000235:genetics / Q000378:metabolism*; D018793:Interleukin-13 / Q000235:genetics / Q000378:metabolism*; D015847:Interleukin-4 / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013666:Tears / Q000166:cytology / Q000378:metabolism*; D018417:Th1 Cells / Q000378:metabolism*; D018418:Th2 Cells / Q000378:metabolism*
D018793:Interleukin-13; D012333:RNA, Messenger; D018799:Intercellular Adhesion Molecule-1; D015847:Interleukin-4; D007371:Interferon-gamma