Lymphoma Lymphoma Basics

Lymphoma Classification: Making Sense of a Complex Disease

A lymphoma is a cancer arising from cells known as lymphocytes, which are a type of white blood cell. For doctors and patients alike, the diagnosis and classification of lymphomas is complex and often confusing. These complexities arise because of advances in our understanding of how normal lymphocytes and lymphomas themselves develop. To understand lymphomas and lymphoma classification, one first must understand something about normal lymphocytes.

What are Normal Lymphocytes?
As a member of the white blood cell family, lymphocytes normally help fight infection. Lymphocytes are divided into two major groups: B lymphocytes (B cells) and T lymphocytes (T cells). When the body is challenged by an infection or other threat, B cells can change into different cells, called plasma cells. The role of transformed B cells (plasma cells) is to secrete antibodies. Antibodies are proteins which attach to infectious or other harmful particles (known as "antigens"). When other white blood cells recognize antibodies which are attached to antigens, these white cells will attack and destroy the particles.

T cells, on the other hand, are responsible for orchestrating the immune response and are also one of the cells which can attack foreign particles. They are helpful in eliminating viruses and tumor cells in the body by binding directly to antigens on these organisms and tumor cells. Unlike B cells, T cells do not secrete antibodies.

There are many, many T and B cells in the body. These cells circulate throughout the body, passing through lymph nodes and the spleen, as they look for "foreign" antigens to which they can react. Once they find an antigen, the lymphocytes become "stimulated" and divide rapidly to make other cells. If these stimulated cells are B cells, they also turn into plasma cells and begin secreting antibodies.

During an infection or other threat, many different B cells and T cells can recognize different pieces of an antigen, causing each of them to proliferate. This results in many large groups of T and B lymphocytes. The end result is a lot more lymphocytes, which can cause lymph nodes (the place where lymphocytes congregate) to enlarge. This is why swollen "glands" (which are lymph nodes), often mean an infection is present.

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