Origin
Human Body
They patrol the entire body, attacking as soon as they spot Cancer Cells or viuses. Natural killer cells or NK cells are a type of cytotoxic lymphocyte critical to the innate immune system. The role NK cells play is analogous to that of cytotoxic T cells in the vertebrate adaptive immune response. NK cells provide rapid responses to viral-infected cells, acting at around 3 days after infection, and respond to tumor formation. Typically, immune cells detect major histocompatibility complex (MHC) presented on infected cell surfaces, triggering cytokine release, causing lysis or apoptosis. NK cells are unique, however, as they have the ability to recognize stressed cells in the absence of antibodies and MHC, allowing for a much faster immune reaction. They were named "natural killers" because of the initial notion that they do not require activation to kill cells that are missing "self" markers of MHC class 1.[1] This role is especially important because harmful cells that are missing MHC I markers cannot be detected and destroyed by other immune cells, such as T lymphocyte cells.
Cells at Work 2nd Season
The cells of the human body never rest for too long; there's always something new to do and learn every day. At least, that's what Hakkekkyuu U-1146 feels as he rushes to and fro, searching for any pathogens that could cause harm to the body. Despite his dangerous line of work, it's all worth it to protect the happy smiles of Sekkekkyuu AE3803, the platelet crew, his fellow neutrophils, and the other cells he meets along the way. In his latest pathogen-hunting adventures, Hakkekkyuu U-1146 discovers how important cells can sometimes make mistakes, and that not all bacteria are actually bad. Everybody has their bad days, but everything eventually works out when their comrades have their backs. In the end, it's just another normal day for these hardworking cells!
Cells at Work
This is a story about you. A tale about the inside of your body... According to a new study, the human body consists of approximately 37 trillion cells. These cells are hard at work every day within a world that is your body. From the oxygen-carrying red blood cells to the bacteria-fighting white blood cells, get to know the unsung heroes and the drama that unfolds inside of you! It's the oddly relatable and interesting story that is the life of cells! (Source: Aniplex USA)
