Systemic Lupus Erythematosus

To the Editor: In the Mechanisms of Disease article on systemic lupus erythematosus (SLE), Tsokos (Dec. 1 issue) 1 notes that a lack of C1q leads to deficient clearance of waste material. I would like to add the role of C1q in the regulation of interferon-α production in response to immune complexes. Recently, Santer and colleagues found that interferon-α production of purified plasmacytoid dendritic cells increased after the addition of C1q to SLE immune complexes. 2 In contrast, in the presence of CD14+ monocytes, almost the whole immune complex adhered to monocytes rather than to plasmacytoid dendritic cells in vitro. 2 C1q inhibited . . .