Tumor necrosis factor production capacity as a potentially useful parameter to monitor disease activity in multiple sclerosis

The aim of this study was to develop a test allowing to monitor disease activity in patients with multiple sclerosis (MS). A simple, fast and reliable test was used to assess the cytokine production capacity of blood leucocytes. The whole blood test (WBT) involved in vitro stimulation of a whole blood sample with either the mitogen phytohaemagglutinin (PHA), or specific antigens. We focused our attention on the production of tumor necrosis factor alpha (TNF), because of the possible involvement of this cytokine in MS pathogenesis. Under in vitro stimulation with PHA or MBP, TNF production was found to be significantly higher in patients during the clinical relapses than during remissions. The increment of TNF production correlated with the severity of the relapses, as determined by the modification of Kurtzke EDSS scale. Moreover, each clinical relapse appeared to be preceded by a peak of TNF production. We then retrospectively analysed 21 patients with the relapsing-remitting form of the disease, in whom the WBT was performed every 2-4 weeks, for periods ranging from 16 to 52 months. Seventy-three peaks of TNF production (defined as the doubling or more of the individual baseline value, which was found to be stable for each patient during remissions), and 47 relapses, including 36 objective and 11 subjective, were observed. Forty-seven out of the 73 TNF peaks were followed by or concomitant with a clinical relapse. In 10 out of the 26 cases where no relapse followed the TNF peak, another cause (mainly infections) of increased TNF production was found. Thus, by excluding other causes, the specificity of the WBT, i.e., the probability to develop a relapse when a TNF peak was found to be 74.6% (47/63). The sensitivity of the WBT was 100%, since all the 47 relapses were preceded by a TNF peak. Assessment of TNF production capacity by the WBT may thus be useful in the follow-up of MS patients, particularly for the follow-up of various treatments. Information provided by the WBT may also be useful to orientate the therapeutic decision for an incipient relapse. Earlier treatment is likely to result in an improved prevention of neurological damage.