they are transported to different parts of the body where they are needed like areas of infection
Leukocytes are found in lots of places, including your spleen, an organ in your belly that filters blood and helps fight infections. Leukocytes also can be found in bone marrow, which is a thick, spongy jelly inside your bones.
Your lymphatic (say: lim-FAH-tik) system is home to these germ-fighting cells, too. You've encountered your lymphatic system if you've ever had swollen "glands" on the sides of your neck, like when you have a sore throat. Although we call them "glands," they are actually lymph nodes, and they contain clusters of immune system cells. Normally, lymph nodes are small and round and you don't notice them. But when they're swollen, it means your immune system is at work.