Characterization of cytokine mRNA transcripts in conjunctival cells in patients with allergic conjunctivitis

The host response to allergens appears to be regulated by specific patterns of local cytokine production. More than 20,000 conjunctival superficial cells were collected with a special brush, a smaller version of the Cytobrush used in cervical cytology, from the upper palpebral conjuntiva.

Samples were obtained by cytology brush from seven patients with allergic conjunctivitis and from seven healthy volunteers. Giemsa staining, immunocytochemistry, and flow cytometric analysis were performed. Cytokine gene expression was assayed by the reverse-transcription-polymerase chain reaction method.

Giemsa staining of cytocentrifuged preparations from patients with allergic conjunctivitis showed conjunctival epithelial cells with lymphocytes, mast cells, and eosinophils. In an immunohistochemical study, a few CD3- and CD4-bearing cells, but not CD20- and CD14-bearing cells, were seen in patients. In 82.6 +/- 17% of the samples obtained from allergic patients, HLA-DR was present, but it was present in only 34.2 +/- 17.8% of samples from control subjects (P = 0.0001) using flow cytometric analysis. Steady state transcripts of mRNA for cytokines were analyzed with RT-PCR in conjunctival cell samples, and results showed that samples from allergic conjunctivitis expressed increased transcripts of interleukin 4 and interleukin 13 but virtually no interleukin 2 or interferon-gamma; six samples from seven healthy subjects expressed no interleukin 2, interleukin 4, interleukin 13, or interferon-gamma transcripts.

These results suggest that the clinical features of allergic conjunctivitis in humans are associated with a specific local pattern of proinflammatory cytokine expression.