How does cell-free DNA reach the blood? - Part 1

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 Welcome back reader! Today, we will look at how DNA reaches the bloodstream. There are two ways by which cells release DNA. One is when living cells release DNA under certain conditions such as stress or as defense. This is called as active release of DNA. Second, when cells die, they release their contents into the surroundings. This is called passive release of DNA. 

Now, how can a cell actively release DNA into blood? There are many processes by which living cells can release DNA. 

Active cfDNA release


First is phagocytosis. Phagocytosis is a process by which white blood cells eat dead or infected cells and bacteria to protect the body from infection. Some of the types of white blood cells that usually do phagocytosis are monocytes, macrophages and neutrophils.

Second is NETosis vital. Now imagine a man is fishing. What would he do if he wants to catch a large amount of fish at once? Throw a net, right? In the same way, neutrophils throw NETs to catch any bacteria or similar microbes that enter our body.  "NET" stands for neutrophil extracellular  traps. They are a combination of DNA and protein. This process of releasing NETs is called NETosis. NETosis can be of two types: vital and suicidal. In NETosis vital, the neutrophils remain alive after NETosis. But, in NETosis suicidal, the neutrophil dies after NETosis.     

Third way by which cells release DNA is secretion of DNA through vesicles. I have explained cell-free DNA released through vesicles in my previous post.  

In my next post, we will discuss how DNA is released passively by cell death. If you have any comments or queries, please post them in the Comments section below!

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