Pathophysiology
Immunoglobulin (Ig) molecules contain two linked heavy chains, with one light chain attached to each (Figure 1). Normally, plasma cells produce immunoglobulins to fight infection (Figure 2). However, monoclonal myeloma plasma cells proliferate and overproduce M protein (abnormal IgG, IgM, or IgA, or rarely IgE or IgD). Multiple myeloma cells also produce abnormal light chain proteins (κ or λ), cytokines that stimulate osteoclasts and suppress osteoblasts, and angiogenesis factors that promote new blood vessel formation. Therefore, the multiple myeloma process leads to an excessive M protein level, which causes hyperviscosity; light chain proteins that cause end-organ damage, especially in the kidneys; and invasive bone lesions
Immunoglobulin (Ig) molecules contain two linked heavy chains, with one light chain attached to each (Figure 1). Normally, plasma cells produce immunoglobulins to fight infection (Figure 2). However, monoclonal myeloma plasma cells proliferate and overproduce M protein (abnormal IgG, IgM, or IgA, or rarely IgE or IgD). Multiple myeloma cells also produce abnormal light chain proteins (κ or λ), cytokines that stimulate osteoclasts and suppress osteoblasts, and angiogenesis factors that promote new blood vessel formation. Therefore, the multiple myeloma process leads to an excessive M protein level, which causes hyperviscosity; light chain proteins that cause end-organ damage, especially in the kidneys; and invasive bone lesions