Introduction & Taxonomy of Immunology Practice Test

Lysosomes are the cell’s digestive compartments that house degradative enzymes such as proteases, nucleases, and lysozyme. In phagocytes, the phagosome fuses with a lysosome to form a phagolysosome, creating a microbicidal environment. Here, the same space contains not only these enzymes but also antimicrobial reactive species: reactive oxygen species like superoxide generated during the respiratory burst, and reactive nitrogen intermediates produced by nitric oxide synthase. These reactive molecules work together with the hydrolytic enzymes to break down and kill ingested microbes. Because all of these components can be found in the lysosome/phagolysosome, the best answer is all of the above.