title: Resolving a case of concurrent hepatitis B virus surface antigen (HBsAg) and surface antibody (HBsAb).
abstract: BACKGROUND
  In most cases, patients appear to recover from acute hepatitis B virus (HBV) infection and do not exhibit the surface antigen (HBsAg). Chronic carriers are positive for HBsAg but HBsAb is usually not present. After acute infection only HBsAb remains. The presence of both HBsAg and HBsAb is unusual.
  
  
  METHODS
  We report on a patient whose results were analytically and clinically discrepant--positive for HBsAg and HBsAb on one testing platform but only HBsAg on another platform.
  
  
  RESULTS
  Reasons for this result: 1) Interference from endogenous antibodies; 2) HBsAg is from one strain and HBsAb is from another: and 3) The presence of HBsAb and HBsAg. Growing evidence indicates that both may be present in many patients. Low HBsAb may be neutralized and not recognized by the solid-phase HBsAg in the assay. Likewise, low HBsAg may be neutralized by HBsAb. It remains unclear whether HBsAg is always cleared after acute infection.
  
  
  CONCLUSIONS
  Testing indicated that both HBsAb and HBsAb were present. The data shows that different testing platforms may produce different results depending on the kinetics, the exposure of the capture HBsAg and the extent of endogenous HBAg/HBsAb. We demonstrate a simple way to rule out test interference to presumptively identify true HBsAb.
authors: Department of Pathology and Laboratory Medicine, Santa Clara Valley Medical Center, San Jose, CA, United States. Electronic address: thomas.kampfrath@hhs.sccgov.org.
authors: Thomas
authors: T
authors: Kampfrath
authors: Department of Pathology and Laboratory Medicine, University of Louisville, Louisville, KY, United States.
authors: Saeed A
authors: SA
authors: Jortani
authors: Department of Pathology and Laboratory Medicine, University of Louisville, Louisville, KY, United States; Laboratory Service, Department of Veteran Affairs Medical Center, Robley Rex VA Medical Center, Louisville, KY, United States.
authors: Stanley S
authors: SS
authors: Levinson
mesh_terms: D000328:Adult; D004279:DNA, Viral / Q000235:genetics; D005260:Female; D006510:Hepatitis B Antibodies / Q000032:analysis*; D006514:Hepatitis B Surface Antigens / Q000032:analysis*; D006515:Hepatitis B virus / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D007118:Immunoassay
chemical_list: D004279:DNA, Viral; D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens
keywords: HBsAb; HBsAg; Hepatitis; Infection