Expression of soluble PD-1 in the sera of patients with recurrent genital herpes and its immunologic significance

Objective To determine the concentration of soluble PD-1 (sPD-1) in the sera of patients with recurrent genital herpes (RCH), and to explore the significance of abnormal expression of sPD-1 in RCH. Methods Serum samples were obtained from 88 healthy blood donors, 74 patients with RCH including 34 cases of outbreak-stage RCH and 40 cases of stable-stage RCH. The serum level of sPD-1 was measured by monoclonal antibody labeling and enzyme linked immunosorbent assay (ELISA). Results A significant difference was observed in the serum level of sPD-1 between the patients with RGH and the blood donors (33.06 ± 17.5 μg/L vs. 53.07 ± 26.3μg/L, P < 0.01) and between the patients with outbreak-stage RGH and those with stable-stage RGH (27.47 ± 12.9 μg/L vs. 37.71 ± 19.6 μg/L, P< 0.01). Conclusions There is a low expression of sPD-1 in patients with RGH, which may be one of the mechanisms underlying the escape of HSV- Ⅱ from immunologic surveillance and development of immunological tolerance.