Figure 2

Distribution and density of type I interferon signature scores in systemic lupus erythematosus patients. (a) Distribution of the type I interferon signature scores in 202 systemic lupus erythematosus (SLE) patients measured at baseline. The type I interferon signature score is calculated as the median fold change (relative to a pooled normal healthy donor sample) of the 21-member type I interferon-inducible transcript pharmacodynamic (PD) marker panel for each patient. The cut-off point for an SLE patient scored as type I interferon signature positive was identified at a value of at least 2 (1 on a log₂ scale), as represented by both the red points in (a) and the rightmost density in (b). Patients scored as type I interferon signature negative are represented by the blue points in and the leftmost density in (b). y axis, type I interferon signature score calculated for the 21-member mRNA PD marker panel on a log2 scale. x axis, type I interferon signature score calculated for the 21-member transcript PD marker panel on a log₂ scale. (b) Density plot of the type I interferon signature scores for these 202 SLE patients. Two distributional modes are illustrated, indicating a clear partitioning between the SLE populations of type I interferon signature positive and negative.