Class Switch Recombination Process in Ataxia Telangiectasia Patients With Elevated Serum Levels of Igm Publisher Pubmed



Mohammadinejad P¹ ; Abolhassani H^{1, 2} ; Aghamohammadi A¹ ; Pourhamdi S¹ ; Ghosh S³ ; Sadeghi B¹ ; Kalmarzi RN¹ ; Durandy A⁴ ; Borkhardt A³ Show Affiliations
Source: Journal of Immunoassay and Immunochemistry Published:2015

Abstract

Ataxia telangiectasia (AT) is a rare primary immunodeficiency disorder with various clinical manifestations. Increased serum levels of IgM and recurrent infections, mainly sinopulmonary infections, can be the presenting feature in a number of AT patients and may be initially misdiagnosed as hyper-IgM (HIgM) syndrome. This study was designed to investigate class switch recombination (CSR) as a critical mechanism in B lymphocytes maturation to produce different isotypes of antibody in response to antigen stimulation in AT cases with HIgM presentation. Quantitative IgE production after stimulation by IL-4 and CD40L was considered as an indicator for CSR function. We also compared their results with sex and age matched AT patients without HIgM presentation. We report four AT patients with recurrent infections during infancy and high serum levels of IgM. Laboratory evaluations revealed defective CSR while none of the three AT patients without HIgM presentation had a defect in the CSR process. The characterized defect in AT is a mutation in the ataxia telangiectasia mutated (ATM) gene. This gene may result in CSR defects due to impaired DNA break repair. A special association between AT and HIgM may indicate a new subgroup of AT patients according to their clinical phenotype and CSR condition. Copyright © Taylor & Francis Group, LLC.