Measuring IFN activity in suspected SLE: a valuable step?

Figures & data

Figure 1. As genetically susceptible patients under the influence of to-date incompletely understood environmental factors, progress from the pre-clinical stage to clinical SLE, various cytokines and antibodies are gradually detected in their peripheral blood. As shown in this figure, IFNγ (blue) is an early marker of immune aberration followed by specific autoantibodies (orange) and IFNα (green)

Table 1. Role of interferon in preclinical SLE

IFN category	IFN types	Main IFN-producing cells	Current evidence (iSLE vs healthy controls)
I	IFN-α (12 subtypes) IFN-β IFN-κ IFN-ε IFN-ω	pDCs Keratinocytes [23]	Military longitudinal case-control study [19] High serum IFN-α score in 41 of 55 (74%) iSLE subjects IFN-α score increased up to 44% before SLE classification IFN-α score further increased to 75% at SLE classification “At risk individuals” ANA+ without meeting SLICC criteria [20] 14 of 118 (12%) evolved to SLE at 12 months Increased baseline IFN-α score in PBMC and nonlesional skin lesions. The former was noted to be predictive of progression Cross-sectional studies of individuals with iSLE [21,22] 14 of 29 (50%) expressed a high serum IFN-α score 12 of 24 (50%) expressed a high interferon signature
II	IFN-γ	T and NK cells	Military longitudinal case-control study [19] High IFN-γ levels precede autoantibody accrual and IFN-α activity Increased IFN-γ levels are predictive for SLE classification
III	IFN-λ 1-2-3-4	pDCs Keratinocytes	N/A

IFN: interferon; NK: natural killer; pDCs: plasmacytoid dendritic cells; iSLE: incomplete systemic lupus erythematosus; PBMC: peripheral blood mononuclear cells.

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