Cellular localization and expression patterns of interleukin‐10, interleukin‐4, and their receptors in multiple sclerosis lesions

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Abstract
Cytokines have been shown to play a crucial role in the pathogenesis of multiple sclerosis (MS). However, still limited data are available on the expression of anti‐inflammatory cytokines within the central nervous system (CNS) during MS lesion development. Therefore, we have examined the expression of the anti‐inflammatory cytokines, interleukin‐10 (IL‐10) and IL‐4, and their specific receptors, IL‐10R and IL‐4R, in postmortem human brain tissue obtained from MS patients. Specific patterns of protein localization and expression for both proteins could be observed within active and chronic MS lesions. Strongest IL‐10 immunoreactivity was observed in reactive astrocytes within active demyelinating lesions and the hypercellular rim of chronic active MS lesions. Moreover, perivascular macrophages were immunoreactive for IL‐10 in (chronic) active MS lesions. Most intense IL‐4 immunoreactivity was detected in reactive fibrillary astrocytes within the hypocellular regions of chronic active and chronic inactive MS lesions. Strong immunoreactivity for IL‐10R and IL‐4R was detected on macrophages in both parenchymal and perivascular areas and on reactive astrocytes in active and chronic MS lesions. Our results indicate that IL‐10 and IL‐4 have an active role in CNS immune responses. The specific patterns of protein localization and protein expression for both IL‐10 and IL‐4 in MS lesions at different stages of development suggest that these anti‐inflammatory cytokines and their receptors participate in processes leading to the formation of chronic MS lesions. GLIA 38:24–35, 2002.