AIDS is a disease where immune system has been too weakened to defend itself against infections. AIDS cannot be treated but prevention is there to avoid AIDS
Uncontrolled cell division results in the formation of tumor, which is of two types benign and malignant tumor. It can be treated with the help of chemotherapy, radiotherapy and alpha interferons.
Ability to fight against disease is known as immunity; it is of two types innate immunity and acquired immunity. It can be active or passive immunity. In Autoimmunity self cells of body attack on it. Various organs in our body act like a organ of immune system like lymph node, spleen, MALT.