OBJECTIVETo investigate the expression of programmed death-1 (PD-1) and programmed death ligand-1(PD-L1) in peripheral T-lymphocytes from patients with chronic periodontitis and its significance and to clarify its role in the development of chronic periodontitis.

METHODSA total of 73 subjects were included in the study and divided into three groups, chronic periodontitis(30 cases), chronic gingivitis(25 cases) and 18 healthy controls. The peripheral blood was collected and PD-1/PD-L1 expression in the surface of CD(+)4 T lymphocytes and CD(+)8 T lymphocytes was examined by flow cytometry. Blood samples from 16 chronic periodontitis patients were collected at week 0 and 6 after initial therapy for 6 weeks and PD-1 and PD-L1 expression in the surface of CD(+)4 and CD(+)8 T lymphocytes was also determined by flow cytometry. The data were statistically analyzed.

RESULTSThe percentage of PD-1 expression in CD(+)4 and CD(+)8 T lymphocytes of chronic periodontitis group[(16.7 ± 5.5)%,(20.8 ± 5.1)%]and chronic gingivitis group[(14.2 ± 6.1)%,(14.5 ± 4.3)%]were higher than that of healthy controls[(9.5 ± 2.1)%, (8.1 ± 1.9)%](P < 0.05). The percentage of PD-L1 expression in CD(+)4 and CD(+)8 T lymphocytes of chronic periodontitis group[(24.2 ± 7.1)%,(15.3 ± 6.8)%]and chronic gingivitis group[(12.4 ± 6.0)%,(11.2 ± 5.5)%]were higher than that of healthy controls[(4.7 ± 1.2)%, (3.2 ± 2.3)%] (P < 0.05). The percentage of PD-1/PD-L1 expression in CD(+)4 T lymphocytes and CD(+)8 T lymphocytes of the chronic periodontitis group were significantly decreased after initial therapy(P < 0.05).

CONCLUSIONSThe expression of PD-1 and PD-L1 in peripheral CD(+)4 T lymphocytes and CD(+)8 T lymphocyte of chronic periodontitis patients was up-regulated and was associated with periodontal condition. The initial therapy reduced the expression of PD-1 and PD-L1.