CD40LG exhibits variable XCI escape, particularly in in vitro–stimulated primary CD3+ T cells from both healthy female donors and SLE patients (Wang et al., 2016), and is aberrantly overexpressed in primary T cells and occasionally primary B cells from females with SLE (Desai-Mehta et al., 1996; Koshy et al., 1996; Lu et al., 2007; Hewagama et al., 2013; Wang et al., 2016) and SSc (Lian et al., 2012). Here, CD40LG is linked to systemic lupus erythematosus.