title: Abnormalities of serum-free light chain in patients with primary antibody deficiency in the absence of B lymphocyte clonality.
abstract: OBJECTIVE
  A review of practice to determine whether serum-free light chain (SFLC) assays are helpful in detecting underlying clonal B-cell disorders or amyloidosis in patients with primary antibody deficiency (PAD) and recurrent infection.
  
  
  METHODS
  SFLC were assayed by nephelometry (BN2 nephelometer, Siemens; FREELITE assay, Binding Site). We reviewed SFLC test results recorded in our regional laboratory over a 4-year time period; 20 adults with PAD were identified as having been tested on at least two occasions.
  
  
  RESULTS
  Of 20 patients, 4 with PAD had abnormal serum-free kappa/lambda (K/L) ratios but no evidence of B-cell clonality. We also found extremely low levels of kappa and or lambda (below the limits of reliable detection) in 19/20 PAD cases (mostly common variable immunodeficiency), such that in many, ratios were not calculable.
  
  
  CONCLUSIONS
  The data suggest that the abnormal ratios are generated by an inability to produce and/or secrete SFLCs, particularly kappa FLC. In this small initial study, we seek to highlight PAD cases where a suspicious K/L ratio, typically with very low absolute quantities of SFLCs, most likely points to B-cell dysfunction, rather than to B lymphocyte clonality.
authors.affiliation: Department of Immunology and Immunogenetics, Pathology Sciences, North Bristol NHS Trust, Southmead Hospital, Bristol, UK. Joe.Unsworth@nbt.nhs.uk
authors.forename: David Joseph
authors.initials: DJ
authors.lastname: Unsworth
authors.forename: Michael John
authors.initials: MJ
authors.lastname: Wallage
authors.forename: Esha
authors.initials: E
authors.lastname: Sarkar
authors.forename: Robert John
authors.initials: RJ
authors.lastname: Lock
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000906:Antibodies; D001402:B-Lymphocytes / Q000276:immunology*; D005260:Female; D006801:Humans; D007145:Immunoglobulin kappa-Chains / Q000032:analysis*; D007146:Immunoglobulin lambda-Chains / Q000032:analysis*; D007153:Immunologic Deficiency Syndromes / Q000276:immunology*; D008297:Male; D008875:Middle Aged
chemical_list: D000906:Antibodies; D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains