Soluble and cell surface ICAM-1 as markers for disease activity in multiple sclerosis

Objective - The intercellular adhesion molecule-1 (ICAM-1) is a member of the Ig supergene family. ICAM-1 is expressed on various cells like peripheral blood lymphocytes, endothelial cells or thymic cells and the cell surface form is supposed to be shed into a soluble form. The expression of ICAM-1 is induced by cytokines like Interleukin-1, TNF alpha or interferon gamma. The aim of the study was to investigate whether changes of cell surface and soluble ICAM-1 in the cerebrospinal fluid (CSF) and blood are indicative for disease activity in patients with multiple sclerosis (MS). Material and methods - In all patients with relapsing-remitting MS (relapse: n =31, remission: n = 11) and controls ( n = 13) the expression of cell surface ICAM-1 (c-ICAM-1) was determined by two colour flow cytometry. Soluble ICAM-1 (s-ICAM-1) was measured by ELISA. Follow-up examinations were done 3 months later. Results - In 31 patients with a current relapse we found significantly decreased expression levels of c-ICAM-1 on leukocytes in CSF ( P <0.001) and blood ( P <0.10), when compared to those 11 individuals experiencing remission. In contrast we observed significantly ( P <0.05) increased levels of s-ICAM-1 in CSF of patients with relapses. Comparing patients who had been in remission for more than 4 weeks ( n = ll) with remission lasting longer than 3 months ( n =28) we detected stable c-ICAM-1 expression on CD3 ⁺ T cells in blood. Conclusion - Our results demonstrate for the first time that c-ICAM-1 on CD3 ⁺ T-cells in CSF and blood is an activity marker in MS.