Interleukin-2 binding proteins in sera from normal subjects and multiple sclerosis patients

Area of Science:

• Immunology
• Neuroscience
• Biochemistry

Background:

• Elevated serum levels of interleukin 2 (IL-2) have been previously observed in patients with chronic progressive multiple sclerosis (MS).
• Interleukin 2 plays a crucial role in immune regulation and T-cell activation, making its modulation a potential factor in MS pathogenesis.

Purpose of the Study:

• To investigate the binding of IL-2 to serum proteins in patients with MS.
• To identify the specific serum proteins interacting with IL-2.
• To assess the functional impact of IL-2 binding on its biological activity.

Main Methods:

• Gel chromatography and protein A sepharose affinity chromatography were employed to isolate and purify serum proteins.
• Enzyme-linked immunosorbent assays (ELISAs) were used to quantify IL-2 and its soluble receptor (sIL-2R).
• A CTLL cell assay was utilized to measure the bioactivity of IL-2 in the presence of serum fractions.

Main Results:

• Interleukin 2 in MS patient serum was found to be complexed with various serum proteins.
• Identified binding proteins include antibodies to IL-2, soluble IL-2 receptors, and high-molecular-weight proteins.
• A specific serum fraction containing IgG antibodies to IL-2 demonstrated inhibition of IL-2 activity in a cell-based assay.

Conclusions:

• Serum proteins, including specific antibodies and soluble receptors, bind to IL-2 in patients with MS.
• This binding potentially leads to the immunomodulation of IL-2 activity.
• These findings suggest a novel mechanism of cytokine regulation contributing to the immunopathology of MS.