Intracellular IFN-γ Levels Research Articles

Herpesvirus Seropositivity in Childhood Associates with Decreased Monocyte-Induced NK Cell IFN-γ Production

EBV infection is inversely associated with IgE sensitization in children, and this association is further enhanced by CMV coinfection. In mice, herpesvirus latency causes systemic innate activation and protection from bacterial coinfection, implying the importance of herpesviruses in skewing immune responses during latent infection. Early control of viral infections depends on IFN-gamma release by NK cells, which generally requires the presence of accessory cells. We investigated IFN-gamma production by NK cells in PBMCs from children seropositive (SP) for EBV alone, for both EBV and CMV, or seronegative for both viruses. The ability of classical (CD14(++)CD16(-)) and proinflammatory (CD14(+)CD16(+)) monocytes to induce autologous NK cell IFN-gamma was studied by coculture experiments with enriched CD3(-)CD56(+) cells. Transwell experiments were used to evaluate how monocytes interact with NK cells to induce IFN-gamma synthesis. SP children had a significantly reduced proportion of IFN-gamma(+) NK cells and cognate intracellular IFN-gamma levels, which was more pronounced in CMV-coinfected subjects. Also, resting PBMCs of SP children displayed lower proportions of proinflammatory monocytes. IFN-gamma production by NK cells was dependent on interactions with monocytes, with the proinflammatory subset inducing the highest IFN-gamma. Finally, SP children had markedly lower levels of plasma IFN-gamma, concurrent with in vitro findings. Herpesvirus infections could be one contributing factor for maturation toward balanced Th1-Th2 responses. Our data indicate that early infection by herpesviruses may affect NK cell and monocyte interactions and thereby also influence the development of allergies.

Dermal Exposure to Cinnamaldehyde Alters Lymphocyte Subpopulations, Number of Interferon-γ-Producing Cells, and Expression of B7 Costimulatory Molecules and Cytokine Messenger RNAs in Auricular Lymph Nodes of B6C3F1 Mice

Background: Although the Murine Local Lymph Node Assay (LLNA) is efficient in identifying chemicals with sensitizing potential, there is increasing need for alternative end points. Cinnamaldehyde (CIN) was chosen for evaluation based on its moderate potency and extensive use in fragrance materials. Objectives: The purpose of the present studies is to incorporate some alternative end points, such as phenotypic analysis and cytokine production, into a modified LLNA/irritancy assay (IA) to evaluate the sensitization of female B6C3F1 mice to CIN. Methods: Several nontraditional end points, including the analysis of lymphocyte subpopulations, B7 costimulatory molecule and cytokine messenger RNA (mRNA) expression, and intracellular interferon-γ (IFN-γ) levels, were incorporated into a modified murine local lymph node (LLNA)/irritancy assay (IA) to evaluate the sensitization of female B6C3F1 mice to cinnamaldehyde (CIN). Results: The alternate end points used in these studies support the classification of CIN as a moderately potent sensitizer. Dermal treatment with CIN resulted in an increase in the percentage of B cells in the auricular lymph nodes (ALNs) and expression of the costimulatory molecule, B7-2, on B cells. Lymph node cells also showed increased transforming growth factor-β1, migration-inhibition factor, and mild increases in IFN-γ and interleukin-2 cytokine mRNA expression. Although the increase in IFN-γ mRNA expression did not translate into increased intracellular IFN-γ levels, the absolute number of T cells producing IFN-γ in the ALNs increased. Conversely, the MEST did not classify CIN as a contact allergen. Conclusion: The nontraditional end points used in the LLNA/IA were not as sensitive as the traditional radioisotope method used to assess cell proliferation. However, they may help identify compounds inappropriately classified as sensitizers or nonsensitizers by the LLNA and MEST.

Elevated intracellular IFN-γ levels in circulating CD8+ lymphocytes in patients with fulminant hepatitis

Background/Aims: Fulminant hepatitis usually takes a rapidly progressive course, terminating in death within a short period. Experimental studies have demonstrated that immunological mechanisms play an important role, especially those involving virus-specific CD8+ cytotoxic T lymphocytes and their production of interferon-gamma (IFN-γ). However, there are no immunological markers for prediction of the development of fulminant hepatitis in man.Methods: Peripheral blood lymphocytes from four patients with fulminant hepatitis, six with acute hepatitis and 11 healthy volunteers as normal controls were analyzed. Intracellular IFN-γ production in both CD8 positive and negative T lymphocytes was assessed by flow cytometry.Results: Populations of CD8+ IFN-γ+ T lymphocytes were significantly increased in patients with fulminant hepatitis, as compared with those with acute hepatitis and normal controls. Production of IFN-γ in CD8+ T lymphocytes of patients with fulminant hepatitis was also elevated, furthermore significantly correlating with the prothrombin time (r=−0.64, p<0.01).Conclusions: The capacity for IFN-γ production by CD8+ lymphocytes is up-regulated in fulminant hepatitis, and this may be important for the development of fulminant hepatitis.