Although multiple studies suggest a dysregulated T-cell cytokine production in systemic lupus erythematosus, the cytokine profile in discoid lupus erythematosus (DLE) lesions is unknown.
To characterize the cytokine profile in DLE by immunohistochemical and molecular methods, and to investigate the role of cytokines in the pathogenesis of DLE.
Patients were evaluated clinically, and biopsy specimens of lesional skin were examined by light microscopy. Reverse transcriptase–polymerase chain reaction and immunohistochemical analysis were performed on 11 biopsy specimens. We investigated the presence of interleukin (IL) 2, interferon γ (IFN-γ), IL-4, tumor necrosis factor α, (TNF-α), and IL-1β messenger RNA (mRNA) in 8 biopsy specimens of DLE and compared it with 3 biopsy specimens of normal skin.
Academic referral research hospital.
Eight consecutive patients with a clinical and histologic diagnosis of DLE.
Localized DLE was found in 7 patients and widespread in 1. During the 4 years of the investigation, none of the patients developed systemic lupus erythematosus. We found significantly elevated levels of IL-2 and IFN-γ mRNA in all 8 biopsy specimens of DLE; in contrast, no transcripts of IL-2 or IFN-γ were detected in 3 biopsy specimens of normal skin (P<.01). Similarly, elevated levels of TNF-α mRNA were detected in 8 DLE biopsy specimens, while no TNF-α mRNA was detected in 3 biopsy specimens of normal skin (P<.01). No IL-4 or IL-1 β mRNA was detected in 8 biopsy specimens of DLE lesional skin and 3 biopsy specimens of normal patient skin. Immunohistochemical analysis showed increased staining for IL-2 and IFN-γ receptors, while no detectable IL-4 receptor was found. No cytokine mRNA or cytokine receptor protein was detected in biopsy specimens of normal skin.
These findings suggest that DLE is associated with type 1 cytokines characterized by the expression of IL-2 and IFN-γ. Type 1 cytokines may be critical for induction, development, and maintenance of DLE.