There are a variety of diseases that can affect the plasma cells, the white blood cells which produce antibodies as part of the body's immune response. Amyloidosis is a disorder where the body produces abnormal antibody proteins, which then accumulate in one or many organs. Two other diseases, solitary plasmacytoma and multiple myeloma, occur when plasma cell production is excessive and the extra cells form tumors in the bone marrow. A condition known as monoclonal gammopathy of undetermined significance, or MGUS, causes an increase in protein produced by the body's plasma cells. Some people may develop a rare cancer called Waldenstrom's macroglobulinemia, which is characterized by an overproduction of IgM antibodies.
Patients with amyloidosis have plasma cells which produce abnormal proteins. These proteins then build up in organs such as the liver, heart, or kidneys. As they accumulate, they begin to inhibit the organs' abilities to function properly. There are three main types of amyloidosis: primary amyloidosis where the plasma cells begin to malfunction for no known reason, secondary amyloidosis which is triggered by another disease, and hereditary amyloidosis which occurs in patients with certain genetic abnormalities.
Some diseases cause tumors to form in the bone marrow, where the plasma cells reside. The tumors are the result of myeloma cells, unnecessary plasma cells that form when the body's plasma production gets out of control. In some cases, only one tumor will form in a single bone; this is known as solitary plasmacytoma. Other patients will develop multiple myeloma, a type of cancer which occurs when myeloma cells are present and form tumors in multiple bones. In many cases where a patient starts off with solitary plasmacytoma, the disease will later progress to multiple myeloma.
Another disease that can affect the plasma cells is monoclonal gammopathy of undetermined significance. Patients with MGUS produce abnormal amounts of a certain type of protein, leading to increased protein levels in the blood. These levels often remain stable, however, and do not cause issues for patients with the disorder. Treatment is often unnecessary, and only monitoring of the condition with blood tests is required.
Waldenstrom's macroglobulinemia is a rare cancer that results from increased IgM antibody production by the plasma cells. These antibodies are relatively large, so a high number of them can cause thickening of the blood, a condition known as hyperviscosity. This may lead to circulation problems as well as issues with the nervous system.
