Monoclonal gammopathies: Group of related disorders characterized by a clone of plasma cells or lymphocytes with the capacity to secrete a homogeneous immunoglobulin or its components, which may be recognized as a peak on serum or urine protein electrophoresis.
Most plasma cell dyscrasias (PCDs) develop after affinity maturation has occurred in the germinal center, as the gene sequence of most myeloma cells are hypermutated, exhibit phenotypic features similar to those of long-lived PCs, and are usually distributed in multiple compartments of the bone marrow.
Since both PC and lymphoproliferative disorders can produce M proteins, making the distinction between which type of disorder is responsible for the M protein is critically important and flow cytometry can assist in this process. Diseases of PCs include MGUS, multiple myeloma, and PC leukemia.
In a patient with suspected multiple myeloma, a bone marrow biopsy is normally obtained.
Multiparametric flow cytometry (MFC):
In clinical flow cytometry, cell populations are considered as abnormal if they have an atypical differentiation patterns, increased or decreased expression of normal antigens, asynchronous maturational patterns, or the expression of aberrant antigens.
Discrimination of normal plasma and myeloma cells from other leukocytes: CD38, CD138, CD45, CD19, CD56, and cytoplasmic immunoglobulin light chains in combination with light scatter.