SLE patients with C3 depression have significant higher expression cells number (%) of CD4 + CD279 + (7.109 ± 0.8234%, (N = 69) vs 10.91 ± 1.973%, (N = 22), p = 0.0408) and CD3 + CD279 + (5.245 ± 0.5207%, (N = 66) vs 9.191 ± 1.728%, (N = 22), p = 0.0041). The gene discussed is PDCD1; the disease is systemic lupus erythematosus.