Cells (細胞 Saibō?) are the basic structural, functional, and biological units of all living organisms. Together they form a multicellular organism, thus they are known as the "building blocks of life". However cells are anthropomorphic in Cells at Work! and have their own stories.

There are roughly 37.2 trillion cells in a human body.

Full-Fledged Cells

Cells Functions Known Characters
Red Blood Cells/Erythrocytes Red blood cells delivers oxygen, carbon dioxide and sometimes nutrients all over the body. A young red blood cell is called an erythroblast. AE3803, AA5100, NT4201, DB5963, YO4144, ME0808, AA2153
Platelets/Thrombocytes Platelets closes wounds, fixes blood clogs. Due to their small size, they are depicted as small children. Platelet
White Blood Cells/Neutrophils Neutrophils are highly mobile white blood cells that are the first to react when pathogenic cells enters. They patrol around and remove foreign germs and viruses as quick as possible. U-1146, U-2001, U-2048, U-2626, U-4989, U-1196
Lymphocytes Lymphocytes are a type of white blood cell that resembles the militarily cells in the system, they are capable of fighting all types of pathogenic cells.
  • helper T cells: Act as commanders when a foreign invasion occurs and decides the strategic response for killer T cells to terminate the threats.
  • regulatory T cells: Control the activity of T cells to prevent them from triggering anomalous immune responses.
  • killer T cells: Kills all pathogenic cells under the command of helper T cells.
  • memory T cells: Killer T cells that encountered the same enemies before during a foreign invasion, they can mount a faster, stronger immune response than the others as they are "experienced".
  • natural killer cells: Patrols around the body and kill infected cells on sight.
  • B cells: Produces weapons called antibodies to fight against antigens.
  • memory cells: Remembers the immune responses to antigens and prepare against them when the same antigens invade again.
Helper T Cell, Regulatory T Cell, Killer T Cell, Memory T Cell, Naive T Cell, Natural Killer Cell, B Cell, Memory Cell
Mast Cells/Mastocyte Mast cells release chemicals such as histamines and leukotrienes as a stimulus to excess production of IgE. Mast Cell
Macrophages/Monocytes Macrophages are a type of white blood cell. They terminate stronger bacteria and relays information to the lymphocytes. They are also capable of digesting and cleaning dead cells. They switch to monocytes when they are roaming in the blood vessels. On the other hand, they assist on raising erythroblasts in the bone marrow. Macrophage
Eosinophils/Acidophils Eosinophils are a type of white blood cell. They are capable of multiplying in allergic reactions and parasitic infections. Their main role is to defend and destroy parasites from entering the body. Eosinophil
Basophils Basophils make up to less than 1% of the white blood cells. They can trigger histamines and allergic reactions. The role of basophils are not fully discovered yet. Basophil
Dendritic Cells Dendritic cells collect antigens from bacteria and infected-cells for the immune system and relay information to the lymphocytes. They are also capable of activating naive T cells, which are inactivated T cells. Dendritic Cell
Intestinal Epithelial Cells Intestinal Epithelial Cells absorbs nutrients and water. They also form a barrier against bacterium in the small intestine.
Goblet Cells Mucous secreting cells that secret the viscous substance mucin. Goblet Cell
M Cells/Microfold Cells M Cells live on the surface of the Peyer's patches. They capture bacteria and viruses and hand them to antigen-presenting cells such as dendritic cells. Microfold Cell
Langerhan Cells Langerhan Cells are a type of dendritic cell of the epidermis. They are responsible on signaling the brain when bacteria and viruses enters the body from the skin. They also protect the skin from ultraviolet rays and dehydration. Langerhan Cell
Hematopoietic Stem Cells Hematopoietic Stem Cells makes blood cells such as red blood cells, white blood cells and platelets. Hematopoietic Stem Cell
Thymic Epithelial Cells Thymic Epithelial Cells nurse lymphocytes and help the differentiation of T cells.
Hair Matrix Cells Hair Matrix Cells create hair through cell division
Sebaceous Gland Cells Sebaceous Gland Cells produce sebum.
Melanocyte Melanocytes produce melanin.
Normal Cells Normal Cells multiply through cell division. The oxygen and nutrients are usually delivered to them. Normal Cell
Cancer Cells Normal Cells that are born mutated due to the copying error in their DNA. They multiply uncontrollably and spread to vital organs, endangering the life of the organism. Cancer Cell

Immature Cells

A Progenitor Cell is a newly born cell that has not differentiate into a specific cell type, similar to a baby.

Lympoid Cell Stem

Cells Possible Growth
B Progenitor Immature B Cell
Immature B Cell/Mature B Cell B Cell
NK/T Progenitor Immature Thymocyte, NK Cell
Immature Thymocyte/Mature Thymocyte Helper T Cell, Killer T Cell

Myeloid Cell Stem

Cells Possible Growth
Myeloblast Myelocyte, Basophil, Eosinophil
Myelocyte/Band Cell Neutrophil
Monoblast Macrophages/Monocyte
Proerythroblast/Erythroblast Red Blood Cell
Promegakaryocyte/Megakaryocyte Platelets
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