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Different immune cell types



So, let's branch into a little Haematology in this post.

One of the main component of the immune system, are the immune cells (I usually like to imagine them as little troops of soldiers). Most of us know them as white blood cells. The flow chart above shows the different lineages of the various blood cell types, and to the left, we see the erythrocyte and megakaryocyte. Erythrocytes are basically the red blood cells, while megakaryocytes are the cells which produces platelets (thrombocytes), but we aren't going into details about that.

So for immunology newbies, it may seem a little overwhelming, but its actually quite simple after going through it a few more times.

As we can see, there are 2 main lineages from the multipotent haematopoietic stem cells: myeloid & lymphoid.

In adaptive immunity, it is easy to remember that the small lymphocyte lineages (T and B lymphocytes), all belong to adaptive immunity.

Apart from erythrocytes, megakaryocytes and small lymphocytes, the rest belongs to the innate immune system. It should be noted however, that the dendritic cells are a group of special cells that crosses between the innate and adaptive immunity, but that will be elaborated in another post.

However, sometimes there might be other classifications of these immune cells as well. One example would be granulocytes, which refers to granules containing cells. Looking at the illustration from the chart above, those cells with many dots depicted inside are the granules. So granulocytes includes basophils, neutrophils, eosinophils, macrophages and Natural Killer (NK) cells. What they basically do, is that upon contact with pathogens, granulocytes releases their intracellular granules to destroy the pathogen.

Another classification is phagocytes, and these are the cells which phagocytose (engulfs) pathogens. Not indicated in the chart above, main phagocytes includes macrophage, neutrophils, tissue dendritic cells and mast cells.

Each different cell types have their own different and specific functions and characteristics. Without any certain immune cell type, it can compromise our immune systems which then leads to many diseases.

So the next time you're upset, remember, your body has an entire system and cell lineages dedicated to maintaining your well-being. 😉

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