Let’s review the cells of your immune system: especially important as we move into cold and flu season, and back-to-school germ-swaps!
WBC is the total number of white blood cells. It includes all 5 types of white blood cells: neutrophils, lymphocytes, monocytes, basophils and eosinophils. Together these make up only about 1% of your blood cells, but it is a very important 1% because your white blood cells fight microbes such as bacteria, viruses, and fungi. They also trigger inflammation if you are injured, as the first stage of the healing process. It is fascinating to watch white blood cells during live blood analysis: you can see them propelling themselves across the microscope slide!
If your white blood cell count is a little high, you are probably fighting an acute infection. If it is a little low, you may be fighting a low-level chronic infection. A low white blood cell count also means that you may be more susceptible to infections, because your defences are below par.
If your WBCs always tend to run low, have a blood test when you have a cold, to see whether they’ve increased as part of your immune response.
White Blood Cell Differential:
The differential is the list you’ll see below the total WBC count. It tells you how many of each of the 5 different types of WBC were seen.
Although some white blood cells are relatively specific in their jobs, WBCs mostly work as tag teams against a variety of microbes. So unfortunately we can’t say “if this type is high we know it is this problem, and only this”: it isn’t that specific.
Neutrophils make up the largest proportion of our WBCs: 40-70%. They mainly work to kill bacteria, and some viruses, parasites and fungi. They are some of the first immune cells to respond.
Lymphocytes make up about 25% of your WBCs, and come in two types. B lymphocytes fight bacteria, viruses and other infectious bugs. Some turn into memory cells. These remember all the germs they have ever encountered. If they see them again, they know how to deal with them. That’s why you can only get measles once, and one vaccination can prevent it: the vaccination triggers that memory, in place of the bug.
T lymphocytes help manage the body’s immune response, and help kill tumour cells. Most need to be activated by another immune cell (there’s the tag-team), and they then morph into a subtype of T cell specific to the job at hand: killing microbes or making antibodies. They are also involved in completing the immune response once the job is done.
Monocytes find and destroy bugs in your blood and your tissues: bacterial, viral, parasitic or fungal. When they leave the blood stream and go into tissues they are called macrophages. They are also part of the clean-up brigade, getting rid of infected cells and helping heal wounds. Far less commonly they can indicate significant disease such as Mononucleosis (“Mono”), auto-immune conditions, some blood disorders or cancers.
Eosinophils are associated with allergic reactions and parasitic infections. Think hayfever and eczema, or digestive problems due to parasites.
Basophils are immune watch-dogs, patrolling for foreign organisms the immune system hasn’t seen before, and gobbling them up when they find them. Basophils contain histamine in their granules, so they tend to indicate allergies, or other inflammation.
Most of this information is general, not absolute, and there is more that can be learned from this panel than just the above brief summary. We can also learn from the ratios of white blood cell counts: they can be used to help follow the progress of some diseases and treatments. But that’s a deeper dive than this.
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