Final answer:
NK cells (natural killer cells) contain cytotoxic granules and are responsible for the destruction of virally infected cells and tumor cells by detecting 'missing self' in these cells, which is characterized by reduced levels of MHC molecules.
Step-by-step explanation:
The leukocyte that contains cytotoxic granules and is often involved in the interaction with cells infected by viral particles is not neutrophils, basophils, or eosinophils, but rather NK cells (natural killer cells). NK cells are a type of lymphocyte, which is a subset of leukocytes that occupy a major role in the innate immune system.
Unlike T cells, NK cells do not require antigen presentation to recognize their targets. Instead, they look for the absence or low presence of MHC (major histocompatibility complex) molecules, which is known as "missing self".
NK cells play a crucial role in the immune response alongside cytotoxic T cells against virally infected cells and tumor cells by releasing cytotoxic granules that can induce apoptosis or cell lysis. Neutrophils, basophils, and eosinophils are also granulocytes, but their primary roles are different: neutrophils are fast-acting phagocytes, eosinophils combat multicellular parasites, and basophils participate in allergic responses.