SIGLEC1 and systemic lupus erythematosus: Interestingly, SIGLEC1 and Ly6E were found to be up-regulated in peripheral blood cells, mainly monocytes, from patients with other autoimmune disorders such as systemic sclerosis and systemic lupus erythematosus compared with healthy controls [25]–[28], and mRNA and protein levels were shown to correlate with disease activity in lupus patients [25], [27], [28].