MX homologous protein in mononuclear cells from patients with systemic lupus erythematosus.
The 76-kd human interferon (IFN)-induced MX protein is the homolog to the murine protein, which is necessary and sufficient to provide adequate resistance to influenza virus infection in murine cells and in mice. Fifty-one patients with systemic lupus erythematosus (SLE) were screened for the presence of the MX homolog in mononuclear cells and for IFN and anti-IFN antibodies in serum. In 47 of 51 patients, significant levels of the MX homolog were found, while only 15 of 51 patients had measurable alpha-IFN in their serum. The IFN activity found in these sera was characterized as a partially acid-labile alpha-IFN, by means of acid-stability cross-reactivity on heterologous cells, trypsin sensitivity, and neutralization by homologous or heterologous antisera. Four of the patients had no detectable MX homolog in their leukocytes; 3 of these 4 possessed an anti-alpha-IFN antibody that was able to neutralize both a natural alpha-IFN preparation and the acid-labile IFN in SLE sera. Also, acid-labile alpha-IFN-containing SLE sera induced the MX homolog in vitro in mononuclear cells from healthy donors. These observations suggest that endogenously produced alpha-IFN is responsible for the observed induction of the MX homolog in SLE and that the IFN system is activated in more than 90% of SLE patients.
von Wussow
P
P
Abteilung Immunologie und Transfusions-medizin, Medizinische Hochschule Hannover, Federal Republic of Germany.
Jakschies
D
D
Hochkeppel
H
H
Horisberger
M
M
Hartung
K
K
Deicher
H
H
D000906:Antibodies / Q000032:analysis; D000998:Antiviral Agents / Q000097:blood*; D001681:Biological Assay; D001798:Blood Proteins; D003588:Cytopathogenic Effect, Viral; D019204:GTP-Binding Proteins; D006801:Humans; D066298:In Vitro Techniques; D007370:Interferon Type I / Q000032:analysis / Q000276:immunology / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000276:immunology; D064547:Myxovirus Resistance Proteins; D009369:Neoplasms / Q000097:blood / Q000276:immunology; D011863:Radioimmunoassay
D000906:Antibodies; D000998:Antiviral Agents; D001798:Blood Proteins; D007370:Interferon Type I; C579070:Mx1 protein, mouse; D064547:Myxovirus Resistance Proteins; D019204:GTP-Binding Proteins