Highly sensitive, automated immunoassay for immunoglobulin free light chains in serum and urine.
BACKGROUND
Bence Jones proteins or monoclonal immunoglobulin kappa and lambda free light chains (FLCs) are important markers for identifying and monitoring many patients with B-cell tumors. Automated immunoassays that measure FLCs in urine and serum have considerable clinical potential.


METHODS
Sheep antibodies, specific for FLCs, were prepared by immunization with pure kappa and lambda molecules and then adsorbed extensively against whole immunoglobulins. The antibodies were conjugated onto latex particles and used to assay kappa and lambda FLCs on the Beckman IMMAGE protein analyzer.


RESULTS
The unconjugated antibodies showed minimal cross-reactivity with intact immunoglobulins or other proteins. With latex-conjugated antibodies, kappa and lambda FLCs could be measured in normal sera and most normal urine samples. Patients with multiple myeloma had increased concentrations of the relevant serum FLC, whereas both FLCs were increased in the sera of patients with systemic lupus erythematosus.


CONCLUSIONS
We developed sensitive, automated immunoassays for kappa and lambda FLC measurements in serum and urine that should facilitate the assessment of patients with light chain abnormalities.
Department of Immunology, The Medical School, Edgbaston, Birmingham B15 2TT, United Kingdom. a.r.bradwell@bham.ac.uk.
A R
AR
Bradwell
H D
HD
Carr-Smith
G P
GP
Mead
L X
LX
Tang
P J
PJ
Showell
M T
MT
Drayson
R
R
Drew
D000818:Animals; D000918:Antibody Specificity; D001322:Autoanalysis; D006801:Humans; D007118:Immunoassay; D007145:Immunoglobulin kappa-Chains / Q000097:blood* / Q000276:immunology / Q000652:urine*; D007146:Immunoglobulin lambda-Chains / Q000097:blood* / Q000276:immunology / Q000652:urine*; D007840:Latex; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D009101:Multiple Myeloma / Q000276:immunology; D009391:Nephelometry and Turbidimetry; D012015:Reference Standards; D012680:Sensitivity and Specificity; D012756:Sheep; D008258:Waldenstrom Macroglobulinemia / Q000276:immunology
D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains; D007840:Latex