CD4 and systemic lupus erythematosus: CD16+ and CD16− monocytes from SLE patients were both potent at promoting CD4+ T cells to differentiate into Treg cells, although CD4+ T cells cocultured with CD16+ monocytes demonstrated weak effects on Treg responses than did CD4+ T cells cocultured with CD16− monocytes (P < 0.01) (Figure 4D).