Immunoglobulin free light chains in severe asthma patient: Could they be a new biomarker?

BackgroundIncreasing evidence is available about the presence of increased serum concentration of immunoglobulin (Ig) free light chains (FLCs) in both atopic and non-atopic inflammatory diseases, including severe asthma, providing a possible new biomarker of disease.MethodsWe analyzed clinical and laboratory data, including FLCs, obtained from a cohort of 79 asthmatic subjects, clinically classified into different GINA steps. A control group of 40 age-matched healthy donors (HD) was considered. Particularly, HD have been selected according to the absence of monoclonal components (in order to exclude paraproteinemias), were tested for total IgE (that were in the normal ranges) and were negative for aeroallergens specific IgE. Moreover, no abnormality of common inflammatory markers (i.e., erythrocyte sedimentation rate and C-reactive protein) was detectable.ResultsFLC-k levels were significantly increased in the asthmatic population, compared to the control group. Despite the absence of statistically significant differences in FLC-lambda levels, the FLC-k/FLC-lambda ratio displayed remarkable differences between the two groups. A positive correlation between FLC-kappa and FLC-lambda levels was found. FLC- lambda level displayed a significant negative correlation with the FEV1 value. Moreover, the FLC-kappa /FLC- lambda ratio was negatively correlated with the SNOT-22 score and a positive correlation was observed between FLCs and Staphylococcus Aureus IgE enterotoxins sensitization.ConclusionsOur findings confirmed the role of FLCs in asthma as a potential biomarker in an inflammatory disease characterized by different endotypes and phenotypes. In particular, FLC-kappa and FLC-k/FLC-lambda ratio could be a qualitative indicator for asthma, while FLC-lambda levels could be a quantitative indicator for clinical severity parameters.This study aimed to describe clinical and laboratory.characteristics of a population of patients with asthma and to investigate the potential