CD46 and Autoimmunity: Two forms of CD46 have been described: membrane and soluble (sCD46), but no conclusive evidence is documented in the literature to show whether posttranslational events or alternative splicing produces the soluble form [41], whose levels have been shown to be increased in the serum of patients with autoimmune disorders including Sjogren's syndrome [42], systemic lupus erythematosus [43], and MS [44].