Methods. In a 24-month prospective study, we used a sensitive enzyme-linked immunosorbent assay to determine levels of TNF-alpha in cerebrospinal fluid and serum in 32 patients with chronic progressive multiple sclerosis and in 20 with stable multiple sclerosis and 85 with other neurologic diseases. An attempt was made to relate TNF-alpha levels with the degree of disability of the patients with multiple sclerosis and with their neurologic deterioration during the 24 months of observation.

Results. High levels of TNF-alpha were found in the cerebrospinal fluid of 53 percent of the patients with chronic progressive multiple sclerosis and in none of those with stable multiple sclerosis (P < 0.001). TNF-alpha was detected in the cerebrospinal fluid of 7 percent of the controls (P < 0.01) with other neurologic disease. In patients with chronic progressive multiple sclerosis, mean TNF-alpha levels were significantly higher in the cerebrospinal fluid than in corresponding serum samples (52.41 vs. 11.88 U per milliliter; range, 2 to 178 vs. 2 to 39; P < 0.001). In these patients, cerebrospinal fluid levels of TNF-alpha correlated with the degree of disability (r = 0.834, P < 0.001) and the rate of neurologic deterioration (r = 0.741, P < 0.001) before the start of the study. Cerebrospinal fluid levels also correlated with the increase in neurologic disability after 24 months of observation (r = 0.873, P < 0.001).

Conclusions. These data provide evidence of intrathecal synthesis of TNF-alpha in multiple sclerosis and suggest that the level of TNF-alpha in cerebrospinal fluid correlates with the severity and progression of the disease. Our results suggest that TNF-alpha may reflect histologic disease activity in multiple sclerosis and could be used to monitor outcomes or responses to therapy.