Porphyromonas gingivalis antigens differently participate in the proliferation and cell death of human PBMC.

OBJECTIVE: Modulation of cell-mediated immunity by microorganisms in periodontal diseases has been widely studied; however, the proliferative activity and/or programmed death of mononuclear cells under periodontopathogenic stimuli are not yet well understood. The aim of this study was to investigate in vitro proliferation and death of peripheral blood mononuclear cells (PBMC) upon stimulation with Porphyromonas gingivalis (Pg) antigens. DESIGN: In 19 patients with chronic periodontitis (CP) and 16 controls without periodontitis (NP) the following clinical parameters were evaluated: bleeding on probing, probing depth, and clinical attachment level. PBMC were cultured under Pg stimuli and apoptosis/necrosis and proliferation assays were carried out for 18 and 48 h, respectively. Fluorescence of labelled cells was determined using flow cytometry. RESULTS: PBMC of CP and NP subjects exhibited a lower proliferative response to Pg LPS (p<0.05) and HmuY protein (p<0.001) compared with non-stimulated cells. Early apoptosis was induced by Pg LPS (p<0.01) and Pg extract (p<0.05), whilst all antigens induced late apoptosis (Pg LPS: p<0.001; Pg extract: p<0.001; HmuY: p<0.01) and necrosis (Pg LPS: p<0.01; Pg extract: p<0.001; HmuY: p<0.001). Pg LPS induced higher late apoptosis than HmuY (p<0.05). Only Pg LPS-induced necrosis tended to be higher in CP compared with NP. CONCLUSIONS: The inhibitory effect of cell proliferation caused by Pg LPS and HmuY protein is not observed when these antigens comprise Pg extract. Despite induced apoptosis, some still unknown mechanism determines the inflammatory outcome in cell death stimulated by HmuY.

Corynebacterium pseudotuberculosis secreted antigen-induced specific gamma-interferon production by peripheral blood leukocytes: potential diagnostic marker for caseous lymphadenitis in sheep and goats.

In the current study, the applicability of the quantification of gamma interferon (IFN-γ) levels for the detection of animals infected with Corynebacterium pseudotuberculosis and for determining caseous lymphadenitis (CLA) clinical status was evaluated. Peripheral blood leukocytes were collected from CLA nonendemic areas animals, from CLA seropositive animals without clinical signs of the disease, and from seropositive animals presenting CLA clinical signs. The leukocytes were stimulated with C. pseudotuberculosis-secreted antigens that were concentrated by the three-phase partitioning technique. An ovine IFN-γ enzyme-linked immunosorbent assay was used to quantify IFN-γ production. Goats and sheep with CLA had higher IFN-γ levels than uninfected seronegative animals. Leukocytes from sheep with CLA chronic abscesses produced higher IFN-γ levels when compared with seropositive sheep without CLA clinical signs, but this difference was not significant in goats. The sensitivity of the assay was 55.8% and 56%, whereas the specificity was 100% and 93%, for goats and sheep, respectively. In conclusion, IFN-γ is a potential marker for the determination of CLA infection status in small ruminants; however, further research is needed to improve assay sensitivity.