Objective: The objective of this study was to determine the levels of interleukin 2 (IL-2), to measure the T cell subpopulations, NK and B cells count in Stage I and II syphilis patients before and after treatment, to analyze the changes in cellular and humoral immunity during the pathogenesis and treatment of the disease, and to further study the role of cellular and humoral immunity during syphilis infection and the relationship between mechanism and prognosis of the disease.
Methods: We divided the experimental subjects into five groups: 100 healthy donors as control, 50 untreated primary syphilis patients, 42 treated primary syphilis patients, 50 untreated secondary syphilis patients, and 46 treated secondary syphilis patients. Fresh anticoagulated blood samples were collected from patients and prepared for T cell subpopulations, B lymphocytes, and NK cell testing using the flow cytometer within 24 h. The serum was separated, and IL-2 levels were measured using the enzyme-linked immunosorbent assay method.
Results: (1) Changes in T-lymphocyte subsets: Comparing the BT I group with the normal, CD4+ T cells increased significantly. In BT II category, the CD4+ T count was significantly low when compared with the control, the CD8+ T cells significantly increased. In AT I group, CD4+ T cells increased significantly. CD4+ T cells reduced in AT II group, CD8+ T cells increased significantly. Comparing AT II and BT II group, the CD4 + T cells of AT II increased significantly, and the CD8 + T cell count of AT II decreased. Comparing BT I and BT II, a significant reduction was observed in CD4+ cells while CD8+ cells increase significantly. CD4+ cells decreased significantly in AT I and AT II comparison, (2) changes in NK cells: There was a significant decrease (P < 0.05) in BT I NK cells against the standard. NK cells count significantly (P < 0.05) higher in BT II and when compared with the control. Among BT II and AT II, NK cells count decreased significantly (P < 0.05) after treatment. There was a significant increase in BT I and BT II NK cells, (3) changes in B cells: B lymphocytes decreased significantly (P < 0.05) in BT II. In comparing BT I and BT II, B cells decreased significantly. Similarly, B cells decreased significantly in AT I and AT II groups comparison, (4) changes in IL-2 levels: Significant changes were noted in
all groups when compared with the normal. IL-2 decreased significantly when BT I and BT II compared.
Conclusions: T cells, NK cells, and IL-2 are involved in the onset and pathogenic mechanisms of the primary and secondary syphilis disease and these cells influence the treatment of the disease. The efficacy of clinical treatment of primary and secondary syphilis patients may be assessed using IL-2 as an alternative surrogate marker.
Key words: Treponema pallidum (syphilis), T lymphocytes, natural killer cells, interleukin-2, BT I (untreated Type I syphilis patients), AT I (treated Type I syphilis patients), BT II (untreated Type II syphilis patients), AT II (treated Type II syphilis patients)