Immune system--What parts of the body are involved?

What parts of the body are involved in the work of the immune system?  Lymphoid organs such as adenoids, tonsils, spleen, thymus and appendix are involved in protecting the body.  The bone marrow (the soft spongy inside part of bones) makes blood cells.  Several types of the white blood cells are important to a properly functioning immune system. The blood vessels carry the blood and blood cells through the body.  You can think of blood vessels as a super highway.  The blood cells travel constantly but when the body signals “foreign invaders present,” the blood cells needed to fight the invaders zoom down the blood vessel highway and get to work protecting the person.  The lymphatic system is the second (lesser known) fluid carrying system of our body.  The lymphatic system contains channels that collect tissue fluids and return the fluids to the blood stream.  Lymph nodes (glands) are small bean shaped organs which store cells which can trap cancer cells and bacteria.  The Ohio State Medical Center shares information about the immune system at http://medicalcenter.osu.edu/patientcare/healthcare_services/infectious_diseases/immunesystem/pages/index.aspx