title: Systemic sclerosis from autoimmunity to alloimmunity.
abstract: BACKGROUND
  The biologic significance of microchimerism from pregnancy in systemic sclerosis and other autoimmune diseases is not fully characterized.
  
  
  METHODS
  We based this brief review on a systematic search of the MEDLINE database for all relevant articles published between 1980 and July 1998, indexing systemic sclerosis, microchimerism, and pregnancy as key words. We also searched textbooks, meeting proceedings, and reference lists.
  
  
  RESULTS
  Fetal microchimerism and class II human leukocyte antigen (HLA) compatibility between mother and fetus are common among women with systemic sclerosis. Alternative sources of microchimerism include the engraftment of donor cells after a blood transfusion, from a dizygotic twin, or possibly from the mother.
  
  
  CONCLUSIONS
  Systemic sclerosis could be a form of chronic graft-versus-host disease caused by fetal or maternal cells, which have crossed the placenta and have remained unrecognized by the host due to class II HLA compatibility.
authors.affiliation: Department of Emergency Medicine, Ospedale San Camillo, Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Famularo
authors.forename: C
authors.initials: C
authors.lastname: De Simone
mesh_terms: D001327:Autoimmune Diseases / Q000276:immunology*; D002678:Chimera; D005260:Female; D005333:Fetus / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D006801:Humans; D007519:Isoantigens / Q000276:immunology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000276:immunology; D012595:Scleroderma, Systemic / Q000276:immunology*
chemical_list: D000949:Histocompatibility Antigens Class II; D007519:Isoantigens