CCR7 and systemic lupus erythematosus: Two transitional monocyte populations (CD14++/CD16+) showed a higher percentage of SSc with double frequency than the other three groups: MC11 (CD16+CD25+CD197−) (HCs: 1.369%; RA: 1.101%; SSc: 2.457%; SLE: 0.994%) and MC12 (CD16+CD25+CD197+) (HCs: 1.081%; RA: 0.844%; SSc: 1.786%; SLE: 0.845%).