Interferon-α biological activity is associated with disease activity and risk of flare in cutaneous lupus erythematosus: A monocentric study of 184 patients.

BACKGROUND

Cutaneous lupus erythematosus (CLE) is associated with unpredictable flares and may induce permanent damage. There is currently no biomarker routinely available in CLE.

OBJECTIVE

To evaluate the performance of interferon-α (IFN-α) biological activity as biomarker of CLE activity and risk of flare.

METHODS

Cohort study including consecutive CLE patients with or without associated systemic lupus erythematosus. Serum IFN-α biological activity (IU/mL) was determined by assessing the antiviral protection afforded by patients' serum.

RESULTS

At first sampling, among 184 included patients, the prevalence of positive IFN-α activity (≥2 IU/mL) was 38%. Positive IFN-α activity was associated with active CLE (odds ratio = 3.11 [95% CI: 1.61-6.01], P = .006), moderate-to-severe CLE activity (odds ratio = 4.43 [95% CI: 1.99-9.86], P = .001) and associated systemic lupus erythematosus (odds ratio = 2.17 [95% CI: 1.19-4.00], P = .01). Among 65 patients with inactive CLE, the risk of CLE flare at 6 months was significantly higher among patients with positive vs undetectable IFN-α activity (hazard ratio 4.95 [95% CI: 1.12-21.78], P = .03). No association was found with anti-double-stranded DNA antibodies and low complement levels.

LIMITATIONS: IFN-α activity is not universally available.

CONCLUSION

IFN-α activity is associated with cutaneous activity and prognosis in CLE and can be used to predict CLE flares in clinical practice.