Korean Journal of Clinical Laboratory Science (대한임상검사과학회지)

Korean Society for Clinical Laboratory Science (대한임상검사과학회)
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Antigen Excess in Free Light Chain Assay U sing the Hitachi 7600 P-module Automatic Chemistry Analyzer

Hitachi 7600 p-모듈을 이용한 유리형경쇄 정량검사의 항원과잉역 반응

  • Cha, Kyong-Ho (Department of Laboratory Medicine, The Catholic University of Korea, Seoul St. Mary's Hospital) ;
  • Kim, Sung-Hee (Department of Laboratory Medicine, The Catholic University of Korea, Seoul St. Mary's Hospital) ;
  • Song, Chang-Un (Department of Laboratory Medicine, The Catholic University of Korea, Seoul St. Mary's Hospital) ;
  • Sim, Yang-Bo (Department of Laboratory Medicine, The Catholic University of Korea, Seoul St. Mary's Hospital) ;
  • Chae, Hyo-Jin (Department of Laboratory Medicine, The Catholic University of Korea, Seoul St. Mary's Hospital)
  • 차경호 (가톨릭대학교 서울성모병원 진단검사의학과) ;
  • 김승희 (가톨릭대학교 서울성모병원 진단검사의학과) ;
  • 송창은 (가톨릭대학교 서울성모병원 진단검사의학과) ;
  • 심양보 (가톨릭대학교 서울성모병원 진단검사의학과) ;
  • 채효진 (가톨릭대학교 서울성모병원 진단검사의학과)
  • Received : 2009.10.28
  • Accepted : 2009.12.16
  • Published : 2009.12.31
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Abstract

The analysis of serum free light chains (sFLCs) can improve the diagnosis and monitoring of multiple myeloma and other plasma cell dyscrasias. As with other immunoassays, sFLCstests are subject to potential antigen excess and heterophilic antibody interference. We describe 9 cases of sFLCs antigen excess in patients with multiple myeloma using the FreeliteTM Human Kappa and Lambda Free Kits (The Binding Site ltd., Birmingham, UK) and the Hitachi7600 P module turbidimetric system. A total of 1,247 consecutive samples from 250 patients with multiple myeloma were assayed for sFLCs from April to September, 2009. The samples were assayed using an initial dilution of 1 :5and subsequent dilutions of 1 :50 and 1: 100. The same samples were analyzed for the presence of monoclonal gammopathies using serum protein electrophoresis (SPE) and immunofixation electrophoresis (IFE). There were 9 samples (0.72%) of antigen excess with 3 cases of kappa (0.24%) and 6 cases of lambda (0.48%). These cases represents an example of antigen excess or "hook effect" using the serum free light chain assays and mandates high level of attention to falsely low sFLC levels due to antigen excess, especially when it is disaccordant to other assay results or clinical manifestations.

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