Also called monoclonal protein, monoclonal immunoglobulin, myeloma protein, or M- spike.
In myeloma, a single B- lymphocyte in the bone marrow undergoes a genetic mutation which causes it to over produce plasma cells in an uncontrolled manner.
These clone plasma cells will continue to produce the same immunoglobulin proteins as the original cancerous cell in large quantities. As a result, an excessive amount of a single type of immunoglobulin is created. The accumulation of this single variety of immunoglobulin is called the M-protein.