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How Normal Plasma Cells Develop

How normal plasma cells develop

Plasma cells are one of many types of blood cells that arise from stem cells in the bone marrow. Plasma cells develop from B lymphocytes (also known as B cells), which are a major class of white blood cells, the blood cells that fight infection in the body. Normally, plasma cells make up about 5% of all cells in the bone marrow.

Plasma cells develop from B cells when foreign substances (antigens), such as bacteria, enter the body. In response to an invasion by foreign substances, groups of plasma cells produce immunoglobulins (also known as antibodies) that help fight off disease and infection caused by the foreign substance. Each plasma cell develops in response to a particular foreign substance within the body and produces immunoglobulins specific to that substance. As a result, many different immunoglobulins are produced in the body.

Each immunoglobulin is made up of four protein chains: two long chains (called heavy chains) and two shorter chains (called light chains). Immunoglobulins are classified into one of five classes according to the type of its heavy chain. Each type of heavy chain has a slightly different function in the body and is defined by the use of a Greek letter. The most common immunoglobulin has gamma heavy chains and is known as immunoglobulin gamma, or IgG. Immunoglobulin alpha (IgA) and immunoglobulin mu (IgM) are the next most common classes of immunoglobulins. The last two classes—immunoglobulin delta (IgD) and immunoglobulin epsilon (IgE)—are present in very small amounts in the blood.

Immunoglobulin light chains are defined by use of the Greek letters kappa and lambda.