title: Value of antibodies to free light chains in immunoperoxidase studies of renal biopsies.
abstract: OBJECTIVE
  Because immunoglobulin abnormalities may affect the kidney, investigation of renal biopsies requires immunohistological study of light chains. A problem is that most antibodies to light chains react with whole immunoglobulins as well as free light chains, and there are generally many more whole immunoglobulins than free light chains. The usefulness of antibodies that only detected free light chains was investigated.
  
  
  METHODS
  Antibodies to free light chains were used in an immunoperoxidase method on paraffin sections of 198 renal biopsies, and compared with conventional antibodies against light chains examined by immunofluorescence on 13 frozen sections and by immunoperoxidase on 46 paraffin sections.
  
  
  RESULTS
  Immunofluorescence and immunoperoxidase were concordant on 10 of 13 biopsies. Immunofluorescence detected slight deposition of light chains in three biopsies not shown by immunoperoxidase, of undetermined clinical significance. Using immunoperoxidase, the free light chain antibodies were more sensitive than conventional antibodies, giving much cleaner staining and better detection of deposits in AL amyloid, light chain deposition disease and cryoglobulinaemic glomerulonephritis. The free light chain antibodies showed discordance or ambiguity between immunohistological and clinical findings in seven (4%) of 185 patients with known immunoglobulin status. These included two of 28 cases of AL amyloid that showed no light chain deposition. The method was not designed for detection of light chain restriction in neoplastic plasma or lymphoplasmacytic cells.
  
  
  CONCLUSIONS
  Polyclonal antibodies to free light chains are an improvement on conventional antibodies in immunoperoxidase study of paraffin sections of renal biopsies and are useful in everyday practice.
authors.affiliation: Department of Histopathology, Wrexham Maelor Hospital, Wrexham, UK.
authors.forename: Mared P
authors.initials: MP
authors.lastname: Owen-Casey
authors.affiliation: Department of Cellular Pathology, Royal Free Hospital, London, UK.
authors.forename: Rosalind
authors.initials: R
authors.lastname: Sim
authors.affiliation: Department of Histopathology, Imperial College School of Medicine, Hammersmith Hospital, London, UK.
authors.forename: H Terence
authors.initials: HT
authors.lastname: Cook
authors.affiliation: Department of Histopathology, Imperial College School of Medicine, Hammersmith Hospital, London, UK.
authors.forename: Candice A
authors.initials: CA
authors.lastname: Roufosse
authors.affiliation: UCL Division of Medicine, National Amyloidosis Centre, Royal Free Hospital, London, UK.
authors.forename: Julian D
authors.initials: JD
authors.lastname: Gillmore
authors.affiliation: UCL Division of Medicine, National Amyloidosis Centre, Royal Free Hospital, London, UK.
authors.forename: Janet A
authors.initials: JA
authors.lastname: Gilbertson
authors.affiliation: Department of Nephrology, Hawke's Bay District Health Board, Hastings, New Zealand.
authors.forename: Colin A
authors.initials: CA
authors.lastname: Hutchison
authors.affiliation: Department of Pathology, University College London, London, UK.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Howie
mesh_terms: D000906:Antibodies; D006801:Humans; D007124:Immunoenzyme Techniques; D007145:Immunoglobulin kappa-Chains / Q000032:analysis*; D007146:Immunoglobulin lambda-Chains / Q000032:analysis*; D007668:Kidney / Q000276:immunology / Q000473:pathology*; D007674:Kidney Diseases / Q000175:diagnosis*
chemical_list: D000906:Antibodies; D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains
keywords: light chains; sensitivity and specificity