The bone marrow is the source of all our blood cells including: red cells (which carry oxygen); white cells (which fight infections); and platelets (which help the blood to clot when needed). The blood cells are continuously released from the bone marrow into the bloodstream.
The lymphatic system is part of the body’s immune system and helps us fight infection. It consists of organs such as the bone marrow, thymus, spleen, and the lymph nodes (or lymph glands). Lymph nodes are connected by a network of tiny lymphatic vessels that contain lymph fluid and are found in groups, particularly in the armpits, the neck and the groin. Some groups of lymph nodes are situated more deeply, in the chest and abdomen. There is also lymphatic tissue in other organs, such as the skin, lungs and intestines.
B-cells are lymphocytes, a type of white blood cell that develop into ‘plasma cells’, which in turn make antibodies to help fight infections. Antibodies are made from a special type of protein called immunoglobulin, and there are five types of immunoglobulins (Ig) in the body: IgG; IgA; IgM; IgD and IgE. Each of these antibodies has a different function and size. Usually, antibodies are made in response to infections in order to help the body fight against them and so develop immunity. IgM is the largest of these, as it circulates in groups of five.
WM arises when an abnormality occurs in B cells as they are in the process of developing into plasma cells.
These developing cells are called ‘lymphoplasmacytic cells’, because they have features of both lymphocytes and plasma cells, which is where the name ‘lymphoplasmacytic lymphoma’ comes from.
In WM, the bone marrow produces abnormal lymphoplasmacytic cells. Although they are of no use to the body, these cells keep being produced. As their numbers increase, they build up within the bone marrow, lymph nodes, spleen and other organs. In the bone marrow the result of this is that the normal blood cells are ‘crowded out’ and this leads to a gradual reduction of normal blood counts. If the build-up occurs in the lymph nodes, spleen or even elsewhere, these tissues swell up and lumps sometimes form that can be visible or felt, although this is not as common as in other lymphomas.