INTERLEUKIN-A BINDING-PROTEINS IN SERA FROM NORMAL SUBJECTS AND MULTIPLE-SCLEROSIS PATIENTS

We previously reported elevations of interleukin 2 (IL-2) in the serum of patients with chronic progressive MS. Using gel chromatography, pr otein A sepharose affinity chromatography, and ELISAs for IL-2 and the IL-2 soluble receptor, we now demonstrate that this cytokine is bound to serum proteins. These serum proteins include antibodies to IL-2, s oluble IL-2 receptors, and high-molecular-weight proteins. Using a CTL L cell assay, a serum fraction corresponding to IgG antibodies to IL-2 inhibited the activity of this cytokine. Thus, we present evidence fo r potential immunomodulation of a pivotal cytokine in MS by serum prot eins.