Specifically, the ratio of regulatory T-lymphocytes cell (CD3+CD4+Foxp3+ Treg) in PBMCs of brucellosis patients determined by flow cytometry before and after treatment showed that after the first and second courses of treatment, the frequency of Foxp3+ Tregs did not significantly change, as the frequency was still higher than that in healthy populations, and there was no significant difference between untreated and treated groups [25]. The gene discussed is CD4; the disease is brucellosis.