MX homologous protein in mononuclear cells from patients with systemic lupus erythematosus

Arthritis Rheum. 1989 Jul;32(7):914-8.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies / analysis
  • Antiviral Agents / blood*
  • Biological Assay
  • Blood Proteins*
  • Cytopathogenic Effect, Viral
  • GTP-Binding Proteins*
  • Humans
  • In Vitro Techniques
  • Interferon Type I / analysis
  • Interferon Type I / immunology
  • Interferon Type I / pharmacology
  • Leukocytes, Mononuclear / metabolism*
  • Lupus Erythematosus, Systemic / blood*
  • Lupus Erythematosus, Systemic / immunology
  • Myxovirus Resistance Proteins
  • Neoplasms / blood
  • Neoplasms / immunology
  • Radioimmunoassay


  • Antibodies
  • Antiviral Agents
  • Blood Proteins
  • Interferon Type I
  • Mx1 protein, mouse
  • Myxovirus Resistance Proteins
  • GTP-Binding Proteins