How Your Immune System Works

Dec 20, 2023


Alto Pharmacy

Your immune system is a network of organs, cells, proteins, and chemicals that work together to keep you healthy. When operating effectively, it protects you from outside threats that cause infection and illness, such as bacteria and viruses. However, a compromised immune system can result in a number of health conditions, including allergies, autoimmune disorders, and immunodeficiency disorders. Here’s what to know.

Immune system components

Your immune system consists of many different pieces that work together to offer protection from germs. These are the main components.

  • White blood cells: These key defenders of your immune system move throughout your body and kick off an immune response when they find bacteria, viruses, parasites, or fungi (also referred to as microbes). There are different types of white blood cells. Two important types to know are B cells and T cells. B cells produce blood proteins called antibodies that attack an invading germ. T cells attack already infected cells in the body, retaining memory of the infection to ensure a fast immune response in the future.

  • Lymph nodes: Part of your body’s lymphatic system, these small glands — of which there are hundreds throughout the body — analyze microbes and stop their spread. Swollen and/or sore lymph nodes indicate that your immune system has been activated and is fighting an infection.

  • Spleen: A small organ located just above your stomach, the spleen stores white blood cells. With blood-filtering properties, it also destroys damaged red blood cells.

  • Tonsils and adenoids: Located in your throat and sinuses, your tonsils and adenoids trap microbes right as they enter the body and offer protection specifically against throat and lung infections.

  • Bone marrow: This is the spongy substance in the center of your bones from which various types of immune cells, including red blood cells, plasma cells, and some white blood cells, are created.

  • Skin and mucous membranes: In preventing germs from entering your body altogether, skin, the body’s largest organ, is your first-line defense against microbes and an important part of the immune system. Mucous membranes lining the respiratory, digestive, urinary, and reproductive tracts also help destroy germs.

  • Stomach and bowel: These organs also play a critical role in keeping you healthy, as acid in your stomach and “good” bacteria in your intestines mobilize quickly to destroy harmful bacteria that has entered the body.

A healthy immune response

A well-functioning immune system can accurately differentiate between outside germs and the body’s own cells, deploying antibodies against external threats. There are two main types of immune responses: innate responses, which happen automatically, and adaptive responses, which require immune cells to learn how to protect you from a specific germ.

An adaptive response does not happen during your initial exposure to a germ. Rather, T cells store a memory of the germ, prompting B cells to deploy antibodies during a subsequent exposure. A healthy immune system will create a stronger, more effective response each time it is exposed to a virus or bacteria.


Vaccines, which were first developed in 1796 for smallpox, build on your immune system’s natural function to protect you from many diseases. They help you develop immunity without the initial health risk of an illness. Some vaccines lower your risk of getting a disease altogether while others lessen its severity.

To trigger an immune response to a specific disease, vaccines imitate an infection, to which your immune system responds just as it would to an actual infection. Detecting antigens from the vaccine, your immune system produces antibodies and T cells. After the imitation infection, T cells and B cells remain in the body and are prepared to quickly fight that antigen in the future. This prevents you from becoming sick if you are exposed to the virus or bacteria that cause the disease.

In most cases, you will not become immediately immune to infection after vaccination, as it typically takes several weeks for your body to produce T cells and B cells in response to a vaccine. This means it is possible to become infected with a disease and develop symptoms shortly after vaccination, so take necessary precautions until you become fully immune to the virus or bacteria. The healthcare professional administering your vaccine will inform you of the anticipated timeline for immunity.

Sometimes the imitation infection created by a vaccine causes mild symptoms such as a fever. These side effects are normal and indicate that your body is building immunity.

Learn more about the CDC’s recommended vaccination schedules for your age group here.

Types of immune system disorders

Some people have immune systems that don’t work properly. There are two main types of immune system disorders: autoimmune disorders and immune deficiency disorders.

Autoimmune diseases occur when the immune system mistakes the body’s own cells for an outside germ and deploys an attack unnecessarily. There are more than 100 of these conditions, with variation in the affected area of the body. Some of the most common autoimmune disorders involve the joints and muscles, digestive tract, nervous system, and skin. While specific symptoms vary by condition, some symptoms are characteristic of a variety of autoimmune disorders, including:

  • Fatigue

  • Joint and muscle pain

  • Rashes

  • Inflammation

  • Digestive issues

  • Swollen glands

Immune deficiency disorders occur when your immune system has a weaker response to germs and other threats and cannot provide adequate protection against illness. There are different types of immunodeficiency, with different causes, including medication, illness, or genetics. HIV/AIDS is a form of immunodeficiency.

How to keep your immune system healthy

Your immune system is shaped by many different factors, including some beyond your control, but there are steps you can take to strengthen your immunity and stay as healthy as possible.

Eat a nutritious, balanced diet

For an immunity boost, prioritize vitamin C-rich fruits and vegetables like oranges, tomatoes, and spinach, along with lean protein, whole grains, and low-fait dairy products. Other immunity-strengthening options include fermented foods and yogurt, which contain probiotics — tiny organisms that help maintain a healthy balance of bacteria in your digestive system. Meanwhile, limit your intake of saturated fats, cholesterol, salt, and added sugars.

Stay active

The many health benefits of regular physical activity include protection from the flu. Struggling to fit exercise into a packed schedule? Building a fitness routine for the first time and unsure where to start? We have tips to help you live an active lifestyle on your terms.

Get enough sleep

Sleep deprivation can interfere with immune system functioning. Studies have found that poor quality sleep or insufficient sleep can leave you more vulnerable to illness and infection and also affect the timeline of recovery. There are many steps you can take to improve your sleep health. As a start, try to maintain a consistent sleep schedule, even on weekends, and unplug from electronics close to bedtime.

Maintain healthy habits

Smoking and heavy alcohol use are both associated with a less effective immune system. Smoking specifically has been associated with an increased risk of rheumatoid arthritis, an autoimmune disease.

If you’re having difficulty making lifestyle changes, try not to be discouraged. Don’t hesitate to reach out to your doctor for resources and support.

Choose a reliable and flexible pharmacy partner

Alto Pharmacy makes it simple to live your healthiest life by providing an easier, more supportive, and more affordable prescription experience.

Our pharmacists have specialized training in treatment for allergies, autoimmune diseases, and HIV, and are here with information and answers, even during nights and weekends. The Alto app gives you control and convenience in managing your medications, with auto refills, medication bundling, and custom dosing reminders.

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This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition.