title: Anti-citrullinated peptide antibodies and rheumatoid factor in Sudanese patients with Leishmania donovani infection.
abstract: OBJECTIVE
  The present study evaluated the presence of anti-cyclic citrullinated peptides antibodies (anti-CCP), rheumatoid factor (RF), and circulating immune complexes (CIC) in Sudanese patients infected with the Leishmania donovani parasite.
  
  
  METHODS
  Sera were collected from Leishmania infected patients (n = 116) and healthy Sudanese (n = 93). Nineteen Sudanese anti-CCP+ RA patients were included as positive controls. Levels of CIC and anti-CCP were measured by ELISA. Control plate with cyclic control peptides containing arginine instead of citrulline was used to evaluate citrulline specifi c reactivity.
  
  
  RESULTS
  Among Leishmania-infected patients and anti-CCP+ RA patients, most were RF positive (86%), while the frequency of CIC positivity was higher among visceral leishmaniasis (VL) patients (VL 38%; anti-CCP+ RA 24%). When anti-CCP reactivity was analysed, 12% of VL patients were found to be positive. The levels of anti-CCP among VL patients correlated well with the CIC levels found (r = 0.65, P < 0.0001). In RA group, no association was found between CIC and anti-CCP. The possibility that anti-CCP positivity was due to cross reactions with CIC was experimentally ruled out. Contrary to what was seen in Sudanese RA sera, the CCP reactivity was not restricted to citrulline but reacted equally well with the arginine control peptide.
  
  
  CONCLUSIONS
  The finding that CCP reactivity was not restricted to citrulline argues that this is more an effect of extensive inflammation and immune activation than a sign of shared pathogenic characteristics with anti-CCP arthritis. Our fi ndings stress the importance to interpret a positive CCP test carefully when evaluated in non-rheumatic conditions or in areas where such infections predominate.
authors: Unidade de Imunologia Clínica, Uppsala University, Suécia.
authors: Erik
authors: E
authors: Ahlin
authors: Amir
authors: A
authors: Elshafei
authors: Musa
authors: M
authors: Nur
authors: Sayda Hassan
authors: SH
authors: El Safi
authors: Ronnelid
authors: R
authors: Johan
authors: Gehad
authors: G
authors: Elghazali
mesh_terms: D000293:Adolescent; D000328:Adult; D000936:Antigen-Antibody Complex / Q000097:blood*; D001323:Autoantibodies / Q000097:blood*; D002648:Child; D005260:Female; D006801:Humans; D007893:Leishmania donovani; D007898:Leishmaniasis, Visceral / Q000097:blood* / Q000276:immunology*; D008297:Male; D010456:Peptides, Cyclic / Q000276:immunology*; D012217:Rheumatoid Factor / Q000276:immunology*; D013397:Sudan; D055815:Young Adult
chemical_list: D000936:Antigen-Antibody Complex; D001323:Autoantibodies; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D012217:Rheumatoid Factor