Changes in human plasma levels of the brain specific oxysterol 24S-hydroxycholesterol during progression of multiple sclerosis.

24S-Hydroxycholesterol (24S-OH-chol) is almost exclusively derived from the brain and the levels of this oxysterol in the circulation may be used as a marker for changes in the turnover of brain cholesterol. In the present study we assayed plasma and cerebrospinal fluid 24S-OH-chol in patients with multiple sclerosis (n = 118) at different stages of the disease. In the oldest groups of patients the levels of 24S-OH-chol were significantly lower than in the controls, possibly reflecting loss of neuronal cells responsible for the synthesis. There was a significant inverse relation between the expanded disability status scale-grade of the disease and the plasma cholesterol related levels of 24S-OH-chol. There was a tendency to increased plasma levels of 24S-OH-chol in the younger patients and almost all of the high levels were found in the patients in the 3rd and 4th decades of life. Increased levels were only found in patients with positive cranial magnetic resonance imaging. The possibility is discussed that plasma levels of 24S-OH-chol may add significantly to existing methods used for evaluation of the different phases of multiple sclerosis.