Prominent B-Cell Signature Differentiates Discoid from Subacute Cutaneous Lupus Erythematosus

Although B cells account for a significant proportion of the lymphocytic infiltrate in discoid lupus erythematosus (DLE), their contribution to pathogenesis is unknown. In this study, we compare the immune landscape of 17 subjects with DLE with that of 21 subjects with subacute cutaneous lupus erythematosus using transcriptomic and histologic analyses of lesional skin. A few of the subjects (3 of 17 subjects with DLE, and 5 of 21 subjects with subacute cutaneous lupus erythematosus) had concomitant systemic lupus erythematosus. Using a modified Autoimmune Profiling Panel (NanoString Technologies, Seatle, WA), we show that B-cell‒specific genes, including canonical pan‒B cell markers CD19 (P = 0.0060), MS4A1 (CD20) (P = 0.0047), and CD79a (P = 0.0201), are among the most upregulated genes in DLE. Numerous other genes encoding B-cell‒associated proteins, including Igs, BAFF receptors, and FCRL family members, are similarly enriched. Relative cell type scoring reveals that among various inflammatory cell types, only B cells are more prevalent in DLE. Digital whole-image slide analysis of immunohistochemistry for B cells (CD20) and T cells (CD3) supports our gene expression findings of a disproportionately greater B-cell infiltrate in DLE lesions. Overall, this study identifies a B-cell‒predominant signature unique to DLE and highlights the importance of studying the role of cutaneous B cells in DLE pathogenesis.