Expression of FcR2/CD23 and p55 IL-2R/CD25 on peripheral blood macrophages/monocytes in multiple sclerosis

Macrophages have been found histologically to be activated in multiple sclerosis. We analyzed the expression of CD23 and CD25 on monocytes/macrophages in peripheral blood obtained from patients with multiple sclerosis (MS) to investigate their role in the demyelinating process. Peripheral blood mononuclear cells were obtained from 30 patients with MS including for Baló's diseases (24 with acute relapsing type disease, six with chronic progressive type disease) and 12 healthy controls. The percentage of CD14⁺ CD23⁺ monocytes/macrophages and CD14⁺ CD25⁺ monocytes/macrophages were determined by two-color flow cytometry. The percentage of CD14⁺ CD23⁺ monocytes was significantly higher in patients with MS in the active phase as compared with controls (P < 0.01). Six patients with acute relapsing MS, who had received no therapy, had higher CD14⁺ CD23⁺ cells than did controls (P < 0.0001). CD14⁺ CD25⁺ monocytes/macrophages were not detected in peripheral blood monocytes/macrophages of patients with MS except Baló's concentric sclerosis. The four patients with Baló's concentric sclerosis had markedly elevated levels of CD14⁺ CD25⁺ monocytes/macrophages. Our findings suggest that monocytes/macrophages are activated during an exacerbatiion of MS. and that they may play an important role in the process of demyelination.