title: A severe case of atypical hemolytic uremic syndrome associated with pneumococcal infection and T activation treated successfully with plasma exchange.
abstract: BACKGROUND
  A severe nondiarrheal form of hemolytic uremic syndrome in children is associated with pneumococcal infection (pHUS). Neuraminidase released by the pneumococci may cleave N-acetylneuraminic acid residues on red blood cells (RBCs), leading to the exposure of the T cryptantigen and polyagglutinability of RBCs, a process known as T activation. Data suggest a pathogenic role of exposed T antigens on glomeruli interacting with naturally occurring anti-T in the development of renal dysfunction in pHUS. By reducing the levels of anti-T and neuraminidase, plasma exchange (PE) may have a role in the treatment of severe cases of pHUS.
  
  
  METHODS
  A previously healthy 2-year-old boy presented with acute renal failure, thrombocytopenia, microangiopathic hemolytic anemia, pneumococcal infection, and T activation of RBCs. A diagnosis of pHUS was made. Due to rapid clinical decline, daily single-volume PE with 5 percent albumin replacement was initiated. Infusion of additional plasma was avoided by using only saline-washed RBCs for transfusion. He made a full recovery after 13 PEs and remained well at follow-up 7 months later.
  
  
  RESULTS
  Polyagglutinability of RBCs was shown by mixing patient RBCs with five normal donor sera. The agglutination assays with a panel of lectins confirmed the specificity of exposed T antigen as the cause of polyagglutinability.
  
  
  CONCLUSIONS
  The dramatic response seen in this patient suggests that PE utilizing albumin replacement may benefit patients with severe pHUS.
authors.affiliation: Division of Transfusion Medicine, Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California 90095-1732, USA. c.k.hopkins@hotmail.com
authors.forename: Courtney K
authors.initials: CK
authors.lastname: Hopkins
authors.forename: Shan
authors.initials: S
authors.lastname: Yuan
authors.forename: Qun
authors.initials: Q
authors.lastname: Lu
authors.forename: Alyssa
authors.initials: A
authors.lastname: Ziman
authors.forename: Dennis
authors.initials: D
authors.lastname: Goldfinger
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000032:analysis*; D001426:Bacterial Proteins / Q000378:metabolism; D002675:Child, Preschool; D003131:Combined Modality Therapy; D003298:Coombs Test; D004903:Erythrocyte Aggregation; D017707:Erythrocyte Transfusion; D006386:Hemagglutination Tests; D006463:Hemolytic-Uremic Syndrome / Q000097:blood / Q000209:etiology / Q000628:therapy*; D006801:Humans; D008297:Male; D009439:Neuraminidase / Q000378:metabolism; D010951:Plasma Exchange; D011008:Pneumococcal Infections / Q000097:blood / Q000150:complications* / Q000188:drug therapy; D012074:Remission Induction; D006435:Renal Dialysis; D012121:Respiration, Artificial; D012709:Serum Albumin / Q000008:administration & dosage; D013296:Streptococcus pneumoniae / Q000201:enzymology
chemical_list: D000900:Anti-Bacterial Agents; D015295:Antigens, Tumor-Associated, Carbohydrate; D001426:Bacterial Proteins; D012709:Serum Albumin; C016467:Thomsen-Friedenreich antigen; D009439:Neuraminidase