Immunoglobulin free light chains in adult atopic dermatitis patients do not correlate with disease severity.

J L Thijs,M S De Bruin-Weller,K Knipping,J Garssen,D J Hijnen,C A F Bruijnzeel-Koomen

doi:10.1186/s13601-016-0132-9

Abstract

BackgroundAlthough total IgE levels have been proposed as a biomarker for disease severity in atopic dermatitis (AD) and are increased in the majority of AD patients, they do not correlate with disease severity during short-term follow-up. During the synthesis of immunoglobulins, free light chains (Ig-FLCs) are produced in excess over heavy chains. In comparison with IgE molecules, Ig-FLCs have a very short serum half-life. Therefore, Ig-FLCs might be more suitable as a biomarker for disease severity during follow-up. Recent studies showed increased serum levels of kappa Ig-FLCs in infants with AD, correlating with disease severity. The aim of this study was to investigate serum kappa Ig-FLC levels in adults with AD, and their correlation to disease severity.MethodsSerum kappa If-FLC and total IgE levels were measured in 82 moderate to severe AD patients and 49 non-atopic controls. Blood was collected from patients before start of treatment with potent topical steroids (European classification: III–IV). 32 patients were treated during a clinical admission, and in this subpopulation a second blood sample was taken after 2 weeks of treatment. Clinical severity was determined by the Six Area Six Sign Atopic Dermatitis (SASSAD) severity score and a panel of serum biomarkers, including thymus and activation-regulated chemokine (TARC).ResultsSerum kappa Ig-FLCs levels in adult AD patients were not increased compared to non-atopic controls. Moreover, we observed no correlation between kappa Ig-FLC serum levels and disease severity determined by SASSAD and a panel of serum biomarkers, including TARC. Serum kappa Ig-FLC levels did also not decrease during treatment.ConclusionThere are no differences in serum kappa Ig-FLC levels between adult patients suffering from moderate to severe AD compared to non-atopic controls. Moreover, serum levels of kappa Ig-FLCs cannot be used as a biomarker for disease severity in adult AD.

Highlights

Total immunoglobulin E (IgE) levels have been proposed as a biomarker for disease severity in atopic dermatitis (AD) and are increased in the majority of AD patients, they do not correlate with disease severity during short-term follow-up
Kappa immunoglobulin free light chains (Ig-FLC) levels measured before treatment did not correlate with disease severity measured by Six Area Six Sign Atopic Derma‐ titis (SASSAD) (r = 0.12, p = 0.30) and Body Surface Area (BSA) (r = −0.05, p = 0.65)
Kappa Ig-FLC levels did not correlate to serum thymus and activation-regulated chemokine (TARC) (r = 0.19, p = 0.30) or any other serum biomarker

Summary

Introduction

Total IgE levels have been proposed as a biomarker for disease severity in atopic dermatitis (AD) and are increased in the majority of AD patients, they do not correlate with disease severity during short-term follow-up. In a cohort of children with severe AD, levels of Ig-FLCs correlated with disease activity [5] These reports prompted us to investigate the role of serum kappa Ig-FLCs in adult AD. Serum levels of kappa Ig-FLCs did not differ significantly between adult AD patients and non-atopic controls. Both kappa Ig-FLC and total IgE levels did not correlate with disease severity

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