26 May 2001
Volume 357, Number 9269
The increased number of endothelial microparticles in people with multiple sclerosis is a marker that "can be tracked and used to study disease activity", says Alireza Minagar (University of Miami School of Medicine, FL, USA). The marker "is almost as accurate as MRI [magnetic resonance imaging] and it's activated on a molecular level, before you see lesions. And it's less invasive and much less expensive than MRI", asserts Minagar.
Minagar and co-workers used flow cytometry to measure endothelial microparticles released into plasma in 50 patients with multiple sclerosis (30 in exacerbation and 20 in remission) and 48 controls. Patients in exacerbation had a 2·85-fold increase in platelet-endothelial cell adhesion molecule-1 (CD31) concentrations compared with controls; during remission, CD31 concentrations returned to values close to those of controls. CD31 concentrations were also positively associated with gadolinium-enhanced lesions seen on MRI (Neurology 2001; 56: 1319-24).
"In patients with multiple sclerosis, you want to know where they stand and how much damage they have. If you monitor and continue to see that microparticles are elevated, then you know you have more active disease and you may need to intervene", says Minagar, who is now studying the marker in his own patients.
But Steven Jacobson, chief of the viral immunology section of the US National Institute of Neurological Disorders and Strokes (Bethesda, MD, USA), warns that such an approach is "premature". "Many questions need to be answered before you can state, as it does in the paper, that 'CD31 is as sensitive as gadolinium enhancement in detecting disease activity.' That's an extraordinarily strong statement that, in my opinion, is not yet supported by the data. We need to ask, for example, what do other inflammatory diseases look like? Is this something that is specific to multiple sclerosis? Do other patients with autoimmune disease also have these elevated numbers during exacerbation?"
What, then, should clinicians tell patients about these findings? "I'd say that it's an interesting observation, but these are laboratory procedures that have to be validated over time and through much larger studies. This is clearly not ready to be a monitoring tool; there are too many holes here", emphasises Jacobsen. "Let's wait to see what it all really means."