Patent ID: 7897353

Claim:
A method of detecting, monitoring or diagnosing a malignant plasma cell disease in a patient, said method comprising obtaining a first sample from said patient; contacting said sample with (i) an antibody, or a Fab or F(ab′) 2 fragment thereof, having specificity for a heavy chain class at the same time as having specificity for a first light chain type; in combination with either: (ii) an antibody, or a Fab or F(ab′) 2 fragment thereof, having specificity for the heavy chain class at the same time as having specificity for a second light chain type; or (iii) an antibody, or a Fab or F(ab′) 2 fragment thereof, having specificity for the heavy chain class and a further antibody, or Fab or F(ab′) 2 fragment thereof, having specificity for the second light chain, wherein one of said first light chain or second light chain is a λ light chain and the other is a κ light chain; conducting an immunoassay on said sample to determine a first ratio between the relative amounts of immunoglobulins having a heavy chain class bound to λ light chains, compared to immunoglobulins having the same heavy chain class but bound to κ light chains; comparing said first ratio to a second ratio, said second ratio comprising the relative amounts of immunoglobins having a heavy chain class bound to λ light chains, compared to immunoglobulins having the same heavy chain class but bound to κ light chains in a) a sample obtained from an individual without the disease, or b) a second sample taken from said patient after said first sample, wherein a deviation of said first ratio from said second ratio indicates the presence of a malignant plasma cell disease and/or the progression/regression of the disease.