T Lymphocytes and B-Lymphocyte Antibodies React Highly Specifically Against Specific Antigens

T Lymphocytes and B-Lymphocyte Antibodies React Highly Specifically Against Specific Antigens-Role of Lymphocyte Clones

When specific antigens come in contact with T and B lymphocytes in the lymphoid tissue, certain of the T lymphocytes become activated to form activated T cells, and certain of the B lymphocytes become acti-vated to form antibodies. The activated T cells and antibodies in turn react highly specifically against the particular types of antigens that initiated their devel-opment. The mechanism of this specificity is the following.

Millions of Specific Types of Lymphocytes Are Stored in the Lymphoid Tissue. Millions of different types of pre-formed B lymphocytes and preformed T lymphocytes that are capable of forming highly specific types of antibodies or T cells have been stored in the lymph tissue, as explained earlier. Each of these preformed lymphocytes is capable of forming only one type of antibody or one type of T cell with a single type of specificity. And only the specific type of antigen with which it can react can activate it. Once the specific lym-phocyte is activated by its antigen, it reproduces wildly, forming tremendous numbers of duplicate lympho-cytes. If it is a B lymphocyte, its progeny will eventu-ally secrete the specific type of antibody that then circulates throughout the body. If it is a T lymphocyte, its progeny are specific sensitized T cells that are released into the lymph and then carried to the blood and circulated through all the tissue fluids and back into the lymph, sometimes circulating around and around in this circuit for months or years.

All the different lymphocytes that are capable of forming one specificity of antibody or T cell are called a clone of lymphocytes. That is, the lymphocytes in each clone are alike and are derived originally from one or a few early lymphocytes of its specific type.