Immunodeficiency: primary or acquired
Quantification of serum free light chain (sFLC) was reported recently to help in the diagnosis of primary immunodeficiencies (PID) and secondary immunodeficiencies (SID) to B lymphoproliferative disorders. Moreover, PID patients are more prone to develop lymphoproliferative malignancies.Ã‚Â
We sought to compare sFLC in PID and SI; and to determine correlation of sFLC with clinical and B cell phenotype.
Clinical and immunological data were collected from 33 PID patients (13 Common Variable Immunodeficiency, CVID and 20 with specific antibody production deficit), 34 SID patients to malignant lymphoproliferation and 13 healthy controls (HC). sFLCs were quantified by nephelometry (FREELITE, Binding-Site, UK).
CVID showed significantly lower kappa/lambda values than SID and HC groups (p-l+ pattern, 2/13 patients; k+l- pattern, 1/13 patients; and k-l- pattern, 10/13 patients. CVID patients with bronchiectasis were more frequent in the k-l- pattern(5 out of 13). 2 CVID patients with detectable sFLC had history of lymphoproliferative disorders. CVID showed lower sFLC than other PIDs, although not significant. Commercial IgG preparations contained detectable sFLCs (mean Ã‚Â k: 41.5 and l: 15.9, respectively), which did not interfered on trough CVID sFLCs. We observed a correlation between sFLC and memory B cell phenotype, the lower the sFLC the lower the class-switched B subset.
sFLC quantification was a useful tool in the diagnosis of CVID over other PIDs, SID and HC. Further studies are necessary to ascertain their potential value as biomarker of malignant lymphoproliferation in CVID.