CD4 and systemic lupus erythematosus: In comparison with non-infectious SLE patients (387.9±261.6/μL), CD4+T cells count decreased significantly in infectious SLE patients (217.8±150.4/μL) (P<0.05), and it was negatively correlated with infection-related indicators including PCT (r=−0.573, P=0.041) and CRP (r=−0.596, P=0.032) levels.