CD4 and systemic lupus erythematosus: In particular, we found CD38 expression levels in SLE significantly increased on circulating plasmacytoid dendritic cells, CD14++CD16+ intermediate monocytes, CD56+ CD16dim natural killer (NK) cells, marginal zone-like IgD+CD27+ B cells, and subsets of central and effector memory CD4+ and especially CD8+ T cells.