In 1200 words review the major aspects of how the human immune system functions. describe How is the proper functioning of this system of major importance to all other systems in the body

in 1200 words review the major aspects of how the human immune system functions. describe How is the proper functioning of this system of major importance to all other systems in the body? What kinds of things can go wrong with the immune function and how do these problems interfere with human life?use apa formate, no plagerism make sure you cite