Types of blood cells
Three types of blood cells with different roles are as follows:
Red blood cells
White blood cells
Platelets
Red blood cells (RBCs)
A fun fact about red blood cells (RBCs) is that they lack a nucleus. Unlike most cells, which contain a nucleus, RBCs are anucleated. This unique feature allows them to maximize their hemoglobin content, enabling the efficient transport of oxygen throughout the body.
When using fluorescence-based cell counters, RBCs cannot be detected because they lack a nucleus. Fluorescent stains typically target the nucleus, so this method excludes RBCs along with other non-nucleated materials like debris. This selective detection is advantageous in applications where nucleated cells are the primary focus.
Interestingly, the hemocytometer—one of the earliest cell-counting tools—was originally developed for counting RBCs. It is used with trypan blue, a dye that stains the entire cell membrane and penetrates the cytoplasm if the membrane is broken, making it useful for counting the total number of cells.
White blood cells (WBCs)
White blood cells (WBCs), also known as leukocytes, are produced in the bone marrow and play a crucial role in the immune system by defending the body against infectious agents. WBCs are classified into three main types: granulocytes, monocytes, and lymphocytes.
However, WBCs are undesirable in stem cell transfusions. If any remain in the transfused material, they can trigger an immune response in the recipient, potentially releasing cytokines—pro-inflammatory substances that can cause fever and other symptoms. Since WBCs contain nuclei, they can be detected and counted using cell counters designed for nucleated cells.
Platelets
Like RBCs, platelets are also anucleated, meaning they lack a nucleus. They are considered cell fragments, as they originate from large bone marrow cells called megakaryocytes. Platelets play a crucial role in clotting and repair by releasing clotting factors to stop bleeding and growth factors to promote healing.
To summarize,
Main function | Nucleus | Diameter | |
RBCs | Transporting oxygen | X | 7 - 9 μm |
WBCs | Immune system | O | 10 - 20 μm |
Platelets | Clotting and repairing | X | 2 - 3 μm |
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