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Soluble and cellular markers of immune activation in patients with systemic sclerosis
D Degiannis1, J R Seibold, M Czarnecki
1Department of Pathology, UMDNJ--Robert Wood Johnson Medical School, Piscataway 08854.
Insights
Systemic sclerosis (SSc) patients show reduced CD8+ T cells and elevated interleukin-2 receptor (IL-2R) expression, indicating ongoing immune activation. Soluble markers like sIL-2R and sCD8 are also increased in SSc.
Area of Science:
- Immunology
- Rheumatology
- Cell Biology
Background:
- Systemic sclerosis (SSc) is an autoimmune disease characterized by immune system dysregulation.
- Understanding lymphocyte subset alterations and activation markers is crucial for SSc pathogenesis.
- Previous studies suggest immune system involvement in SSc, but specific lymphocyte dynamics require further elucidation.
Purpose of the Study:
- To investigate peripheral blood lymphocyte patterns in SSc patients.
- To assess in vitro lymphocyte responses and soluble immune activation markers in SSc.
- To explore the role of laminin in lymphocyte activation in SSc.
Main Methods:
- Analysis of lymphocyte subsets (CD3, CD4, CD8, B cells) and activation markers (IL-2R) in 24 SSc patients and healthy controls.
- In vitro stimulation of peripheral blood mononuclear cells (PBMCs) with PHA and laminin.
- Measurement of soluble interleukin-2 receptor (sIL-2R) and soluble CD8 (sCD8) levels.
Main Results:
- SSc patients exhibited a significantly reduced proportion of CD8+ lymphocytes.
- Elevated expression of IL-2 receptor (IL-2R) on lymphocytes was observed in SSc patients.
- Soluble plasma IL-2R and sCD8 levels were significantly higher in SSc patients compared to controls.
- Reduced proliferative responses to PHA stimulation were noted in SSc patients' PBMCs.
- Laminin exposure increased IL-2R expression on SSc lymphocytes but did not induce proliferation or IL-2 production.
Conclusions:
- The findings suggest an ongoing lymphocyte activation process in systemic sclerosis.
- Alterations in CD8+ T cell proportions and increased IL-2R expression are key indicators of immune dysregulation in SSc.
- Soluble immune markers (sIL-2R, sCD8) serve as potential biomarkers for immune activation in SSc.
Abstract:
The peripheral blood lymphocyte pattern, the lymphocyte responses in vitro, as well as the soluble markers of immune activation were studied in 24 patients with systemic sclerosis (SSc patients). The proportions of total T cells (CD3), their CD4 subset, as well as B lymphocytes were within the normal range. The relative proportion of CD8 lymphocytes, however, was significantly reduced. Patients with SSc had a slightly lower percentage of CD4/4B4+ cells, whereas their proportion of CD4/2H4+ cells was elevated as compared to healthy controls. The proportion of lymphocytes expressing the interleukin-2 receptor (IL-2R) was significantly higher in SSc patients. The proliferative responses of peripheral blood mononuclear cells to PHA stimulation were reduced in the patient group, while expression of IL-2R on lymphocytes after such in vitro stimulation was comparable to that of controls. Expression of IL-2R on patient but not control lymphocytes was increased after in vitro exposure to laminin. Such exposure failed to induce IL-2 production or cell proliferative responses. Soluble plasma IL-2R level (sIL-2R) and soluble CD8 (sCD8) molecule levels in SSc patients were significantly elevated. These results indicate the presence of an ongoing lymphocyte activation in this disease process.