Context: The most well-known disease that affects the immune system itself is AIDS, an immunodeficiency characterized by the suppression of CD4+ ("helper") T cells, dendritic cells and macrophages by the Human Immunodeficiency Virus (HIV).

Question: What is the most famous immune system disease?
Answer: AIDS

Question: What kind of disease is AIDS?
Answer: an immunodeficiency

Question: Which types of cells are suppressed by AIDS?
Answer: CD4+ ("helper") T cells, dendritic cells and macrophages

Question: What virus specifically suppresses those cells?
Answer: Human Immunodeficiency Virus (HIV)