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Cellular immunity in current active pulmonary tuberculosis
R Andrade-Arzabe1, I V Machado, B Fernandez
1Clinical Immunology National Center, Ministry of Health, Caracas, Venezuela.
Insights
Newly diagnosed pulmonary tuberculosis patients exhibit early immune system compromise. Their cellular immunity, including interleukin-2 (IL-2) production, is impaired, suggesting a role in disease progression.
Area of Science:
- Immunology
- Infectious Diseases
- Pulmonology
Background:
- Pulmonary tuberculosis (TB) remains a significant global health challenge.
- Understanding early immune dysregulation in TB is crucial for effective management.
Purpose of the Study:
- To investigate cellular immune mechanisms in patients with newly diagnosed pulmonary TB.
- To compare immune responses with healthy, Bacillus Calmette-Guérin (BCG) immunized individuals.
Main Methods:
- In vitro analysis of peripheral blood mononuclear cells (PBMCs) from 10 TB patients and 10 controls.
- Stimulation with PHA, PPD, and recall antigens (SK/SD, CA) in autologous serum or with depleted adherent cells.
- Measurement of soluble IL-2 receptor and IL-2 synthesis.
Main Results:
- Patient sera inhibited autologous and allogeneic cell responses.
- A significant suppressive effect from adherent cells was observed.
- TB patients showed decreased blast transformation to PPD, low PPD-induced IL-2 generation, and high soluble IL-2 receptor levels.
Conclusions:
- Newly diagnosed pulmonary TB is associated with early compromise in specific cell-mediated immunity.
- Abnormalities in IL-2 pathways and T-cell activation may play a role in TB pathogenesis.
Abstract:
A group of 10 patients with recently diagnosed pulmonary TB were studied and compared to 10 bacillus Calmette-Guérin (BCG) immunized healthy individuals. Cellular immune mechanisms were explored in vitro utilizing fresh and precultured peripheral blood mononuclear cells exposed to PHA, PPD, and recall antigens (SK/SD and CA). Proliferative assays were also carried out in the presence of either each patient's serum (autologous serum) or cocultured with CD3(+)-depleted adherent cells. Serum measurements of soluble interleukin-2 (IL-2) receptor and synthesis of IL-2 generated by mononuclear cells stimulated with PPD and SK/SD were also performed. Patient sera were able to inhibit autologous as well as allogeneic cell responses, and a significant adherent cell suppressive effect was observed. As a whole the group of patients showed decreased blast transformation to PPD, preserved proliferative responses to other recall antigens, and a low PPD-induced generation of IL-2. Furthermore, as possible evidence of preactivated T cells, these patients demonstrated high soluble IL-2 receptor serum levels. Early compromise of specific cell-mediated immunity, including IL-2 abnormalities, may be of significance in newly diagnosed pulmonary TB.