The spleen contains lymphocytes and lymphatic lumps known as follicles. Lymphocyte formation takes place in germinal centers in the white pulp. The spleen, like the lymph nodes, responds to bacteria and other antigens that enter the circulation by releasing phagocytic cells known as macrophages. These cells migrate through blood vessels into the surrounding tissue where they destroy infected cells and release chemicals that trigger inflammation. Lymphocytes are immune system cells that play a crucial role in protecting organisms from infection. Two main types of lymphocytes exist: B cells and T cells. B cells can produce antibodies that bind to foreign particles or cells that have been marked with a tag that identifies them as foreign. This binding prevents further interaction between the body's immune system and these particles or cells. T cells act against viruses, bacteria, protozoa, and cancer cells by triggering an immune response. The spleen is one of the largest lymphoid organs in humans and plays an important role in immune function. It has two main functions: filtering blood to remove waste and abnormal cells, and storing red blood cells before they are needed at physical activity. Men are likely store more blood cells than women because they are required to store more red blood cells during periods of intense exercise or when suffering from anemia. Additionally, men have more lymphocytes and platelets due to the effect of testosterone on bone marrow production.