Characterization of complement receptor type i and type 3 mrna expression on polymorphonuclear leucocytes (neutrophils) in gingival crevicular fluid from periodontitis-affected patients

A previous study has demonstrated that complement receptors on the surface of polymorphonuclear leucocytes (neutrophils) in gingival crevicular fluid significantly increased compared with those in autologous peripheral blood obtained from periodontitis-affected subjects. The present study attempted to determine the mRNA levels of complement receptor types 1 and 3 (CR1, CR3) on neutrophils in gingival crevicular fluid using reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization. Gingival crevicular fluid samples were obtained from 11 adult periodontitis patients by gingival crevicular washing, and venipunctured peripheral blood was used as a control. RT-PCR analysis was performed using the primer sets for CR1, CR3 and β-actin. Digoxigenin-labelled RNA probes were synthesized from RT-PCR products for in situ hybridization. Both CR1 and CR3 mRNA levels relative to β-actin were significantly lower in crevicular fluid neutrophils than in peripheral blood neutrophils (crevicular fluid-CR1: 32.75±22.93%, peripheral blood-CR1: 65.30±43.25%, p < 0.005; crevicular fluid-CR3: 9.09 ± 5.34%, peripheral blood-CR3: 30.14 ± 18.80%, p < 0.005). In in situ hybridization, a greater majority of neutrophils showed positive CR1 and CR3 mRNA expression, while only a few neutrophils showed positive signals in gingival crevicular fluid. Data in the present study suggest that increased expression of complement receptors on the neutrophil cell surface appears to be unrelated to de novo synthesis.