Serum interleukin-15 is elevated in systemic lupus erythematosus

Area of Science:

• Immunology
• Rheumatology

Background:

• Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by immune system dysregulation.
• The role of specific cytokines, such as interleukin-15 (IL-15), in SLE pathogenesis requires further elucidation.

Purpose of the Study:

• To investigate elevated serum levels of IL-15 in SLE patients compared to healthy individuals and rheumatoid arthritis (RA) patients.
• To determine if IL-15 correlates with immunological markers such as CD25 and Bcl-2 expression on lymphocytes in SLE.
• To assess the direct effect of IL-15 on lymphocyte Bcl-2 and CD25 expression.

Main Methods:

• Serum levels of IL-15, IL-2, and TNF were measured using ELISA in 65 SLE patients, 20 healthy controls, and 10 RA patients.
• Lymphocyte CD25 and Bcl-2 expression were quantified by fluorocytometry in 25 SLE patients.
• Peripheral blood mononuclear cells (PBMCs) from 15 SLE patients were cultured with recombinant IL-15 to evaluate its impact on Bcl-2 and CD25.

Main Results:

• Serum IL-15 was significantly elevated in 38% of SLE patients compared to healthy and RA controls (P = 0.0005).
• Increased lymphocyte CD25 and Bcl-2 expression in SLE patients positively correlated with serum IL-15 levels.
• Recombinant IL-15 treatment in vitro led to increased Bcl-2 and CD25 expression on lymphocytes.

Conclusions:

• Elevated serum IL-15 is a feature of active SLE.
• IL-15 may contribute to the immunological abnormalities observed in SLE, including altered lymphocyte phenotype.