Читать книгу Immunology - Richard Coico - Страница 39

The spleen is the largest of the secondary lymphoid organs (Figure 2.4A). It is highly efficient in trapping and concentrating foreign substances carried in the blood. It is the major organ in the body in which antibodies are synthesized and from which they are released into the circulation. The spleen is composed of white pulp, rich in lymphoid cells, and red pulp, which contains many sinuses as well as large quantities of erythrocytes and macrophages, some lymphocytes, and a few other cell types. Figure 2.4B shows a section of human spleen illustrating the red and white pulp areas.

The areas of white pulp are located mainly around small arterioles, the peripheral regions of which are rich in T cells; B cells are present mainly in germinal centers. Approximately 50% of spleen cells are B lymphocytes; 30–40% are T lymphocytes. After antigenic stimulation, the germinal centers contain large numbers of B cells and plasma cells. These cells synthesize and release antibodies.