Expression of the interferon‐induced MxA protein in viral encephalitis

Abstract

MxA protein accumulates cytoplasmically in response to interferon stimulation, and mediates resistance against several viruses. In order to test whether MxA may serve as a diagnostic tool for viral infections of the central nervous system (CNS), we performed MxA immunohistochemistry on biopsies and autopsies of 57 patients with neurological disorders of known viral and nonviral aetiology. MxA was detectable in all HIV patients with proven opportunistic viral encephalitis, in all patients suffering from isolated viral encephalitis, in one of three HIV patients with cerebral toxoplasmosis, and in one case of micronodular encephalitis. No MxA was detectable in HIV patients with isolated HIV encephalitis or HIV infection accompanied by an opportunistic nonviral disorder. We were unable to show MxA expression in a variety of nonviral inflammatory and noninflammatory disorders of the CNS. Several cases of Rasmussen's encephalitis and multiple sclerosis tested negative, arguing against their possible viral aetiology. Two-colour immunohistochemistry identified macrophages and activated microglia as MxA expressing cells. In all studied cases MxA expression was accompanied by a marked T-cell infiltrate. Therefore, the detection of MxA-protein is a sensitive adjuvant marker for those cases of viral encephalitis which are accompanied by pronounced lymphocytic infiltrates.

Immunohistochemical Evaluation of Mx Protein Expression in Canine Encephalitides

“…Although most studies of Mx proteins have focused on their activity against RNA viruses, herpesviruses and other DNA viruses are also capable of inducing MxA production. 6,19,26 The range of cell types that were immunoreactive for Mx protein in this study was greater than in the 2 reports of MxA expression in human encephalitides, including macrophages/microglia, neurons, and astrocytes. In the study by Lampe, Schneider-Schaulies, and Aguzzi, which included cases of HIV, SSPE, and a single case of herpes simplex infection, staining appeared to be restricted to macrophages and microglia.…”

Spontaneous MxA mRNA level predicts relapses in patients with recently diagnosed MS

“…9 Type I IFN pathways play an important role in other chronic inflammatory diseases, such as systemic lupus erythematosus and Sjögren syndrome. [10][11][12] Furthermore, Mx proteins are found in the plaques of treatment-naïve patients with MS 13 and are demonstrated by immunohistochemistry in viral encephalitis, confirming their role in neuroinflammatory processes. In this study, we investigated whether spontaneous (therapy-naive) MxA mRNA expression levels are related to clinical and radiologic measures of disease activity.…”

Increased Number of Islet-Associated Macrophages in Type 2 Diabetes

“…Islet-associated granulocytes were identified morphologically (hematoxylin and eosin staining) and using an anti-human myeloperoxidase antibody (rabbit polyclonal, 1:15,000; Dako). The CD68 antibody was used as previously shown (14) and controlled by mouse IgG antibody staining. For transferase-mediated dUTP nick-end labeling (TUNEL) detection, sections were permeabilized with proteinase K (20 g/ml) and endogenous peroxidases blocked with 3% H 2 O 2 .…”