Soluble interleukin-2 receptor and soluble CD8 molecules in cerebrospinal fluid and serum of patients with multiple sclerosis.

The purpose of this study was to analyse soluble interleukin-2 receptor (sIL-2R) and soluble CD8 (sCD8) molecules in the cerebrospinal fluid (CSF) and serum of 18 patients with definite multiple sclerosis (MS) and of 16 with noninflammatory neurologic diseases (NIND). All MS patients suffered from an exacerbation of the relapsing-remitting form of the disease within one month before examination. The mean serum levels of sIL-2R and sCD8 in the MS patients were not significantly different from those of NIND patients. Only one patient with MS had detectable sIL-2R in the CSF. CSF sCD8 was detectable in 10 of 18 MS patients and in 1 of 16 NIND patients. Our data indicate that the CSF and serum sIL-2R concentrations do not correlate with the disease activity. Conversely, increased levels of sCD8 only in the CSF of MS patients support the hypothesis of an intrathecal activation of CD8+ cells in MS. We think that CSF sCD8 can be a useful marker for the presence of activated T cells in the central nervous system.