Mass spectra of proteins isolated using single domain antibody fragments (SDAF) with affinity for immunoglobulins are used to identify, quantitate, and establish heavy and light chain pairings of M-proteins using MALDI-TOF mass spectrometry. The invention utilizes the unique molecular mass and structure of single domain antibody fragments and the unique molecular mass distributions of heavy and light chain immunoglobulin isotypes to accurately and sensitively identify, isotype, and quantitate monoclonal proteins in patients with plasma cell dyscrasias.
a) Provides a method that is faster, less expensive, less laborious and automatable;
b) Provides an electronic record used for interpretation rather than a gel;
c) Overcomes shortcomings of previous methods in that data acquisition takes less than 15 seconds per sample;
d) Does not require liquid chromatography or electrophoretic separation;
e) Can identify all the major monoclonal isotypes of M-proteins with sensitivity exceeding current methods;
f) Can specifically identify the distribution of kappa and lambda light chains paired with IgM, IgA or IgG heavy chains;
g) Can analyze both the light chains and heavy chains in a single sample and single analysis; h) Can replace the need to concentrate samples prior to analysis due to superior sensitivity; and i) Can replace the need for total protein measurement and protein gel electrophoresis of urine or serum in order to quantitate specific monoclonal proteins.