Pages Menu
TwitterRssFacebook
Categories Menu

Posted by on Jun 14, 2013 in Medical Journals |

Raised tryptase without anaphylaxis or mastocytosis: heterophilic antibody interference in the serum tryptase assay.

Head for The Masto Townhall forum to debate this paper.
This article may be copyrighted. Notice to copyright holders.
You can view the full article at the publisher here
This is a free article and no fee is due to download it.
Clin Exp Immunol. 2011 Mar;163(3):339-45. doi: 10.1111/j.1365-2249.2010.04287.x.

Raised tryptase without anaphylaxis or mastocytosis: heterophilic antibody interference in the serum tryptase assay.

Sargur R, Cowley D, Murng S, Wild G, Green K, Shrimpton A, Egner W.

Abstract

Mast cell tryptase (MCT) is a key diagnostic test for mastocytosis and anaphylaxis. High serum tryptase levels are also one of the risk factors for adverse reaction in venom immunotherapy, yet occasional patients are seen with raised levels in the absence of either diagnosis. False positive results can be due to assay interference by heterophilic antibodies such as rheumatoid factor (RF) and human anti-mouse antibodies (HAMA). We therefore investigated heterophilic antibody interference by rheumatoid factor activity and HAMA as a cause of raised MCT results in the Phadia tryptase assay. Serum samples from 83 patients were assayed for MCT and rheumatoid factor before and after the use of heterophilic antibody blocking tubes (HBT). Samples with more than 17% reduction in MCT with detectable RF were then assayed for HAMA. Fourteen (17%) of the 83 samples with positive RF showed a >17% decrease in mast cell tryptase after HBT blocking. Post-HBT, eight of 14 (57%) reverted from elevated to normal range values with falls of up to 98%. RF levels were also decreased significantly (up to 75%). Only one of the 83 tested was apparently affected by HAMA in the absence of detectable IgM RF. In conclusion, any suspicious MCT result should be checked for heterophilic antibodies to evaluate possible interference. False positive MCT levels can be caused by rheumatoid factor. We suggest a strategy for identifying assay interference, and show that it is essential to incorporate this caveat into guidance for interpretation of MCT results.

© 2011 The Authors. Clinical and Experimental Immunology © 2011 British Society for Immunology.

PMID: 21303361 [PubMed – indexed for MEDLINE] PMCID: PMC3048617 Free PMC Article