Building and Strengthening the Immune System
Your body has a defense system against such invaders. It's called the immune system. Your immune system is made up of trillions of cells and proteins. These are found in your blood and in every organ in your body. The immune system learns and changes throughout your life, even before birth.
Your defenses are not born with a fully equipped immune system. Fetuses may produce some immune protection. But before birth, "the vast majority of protection against infection comes from the mother," explains Dr. Whitney Harrington, who studies immune system development at the Seattle Children's Research Institute.
Germ-fighting molecules produced by the immune system, called antibodies, are transferred to the fetus through the placenta. They can also be transmitted to the baby after birth through breastfeeding. Antibodies attach to germs and prevent them from infecting cells.
“The peak risk of severe disease from many infections is before six months of life,” says Harrington. This is because the baby's immune system is just beginning to develop.
Antibodies that are passed from the mother can last for many months. They help protect a new baby until her immune system begins to develop.
The immune system builds many lines of defense. Cells of the innate immune system provide an early response to danger. They move through the body looking for signs of damage or infection of other cells. They then destroy those cells.
Another important defense is called the adaptive immune system. It is activated by signals from the innate immune system and infectious germs and generates a powerful response. The cells of this system keep a long-term memory of the germs they fight. They also respond to vaccines and make all of their antibodies.
Researchers have discovered that, like antibodies, some adaptive immune cells are also passed from mother to fetus. These cells can begin to teach the fetus's immune system about the germs the mother has been exposed to.
Harrington and her team have been trying to learn more about these cells. They want to understand when this transfer occurs and use it to maximize the immune protection provided by the mother.
Throughout infancy and childhood. Her immune system matures and continues to build its own disease-fighting cells. Exposure to germs in childhood helps the immune system get stronger over time, says Harrington.
Protection as you age
By the time you reach young adulthood, you are exposed to many germs. Therefore, your immune system is likely to have a strong response to many infections you encounter.
Vaccines further strengthen your defenses. Vaccines expose your immune system to killed or weakened germs, or just parts of them. This helps your immune cells learn how to fight these threats and remember them without making you sick.
Certain vaccinations are recommended during pregnancy. These enhance the mother's protection against deadly diseases during the first months of the baby's life. Vaccines are recommended shortly after birth through adulthood.
Some vaccines require additional injections during adulthood to boost your immune system's memory. And some people, depending on their health, job, or other factors, may need additional vaccinations to stay safe.
But, like other systems in your body, your immune system can begin to decline as you age. These changes can prevent immune cells from working as well as they can.
“With age, immune cells lose their ability to respond quickly and robustly to infections,” he says.
Other parts of your body, such as your heart or lungs, can also accumulate wear and tear with age. This reduced function puts older adults at greater risk of developing more serious disease from many infections.
Even a little more damage from an infection can cause an older adult's organs and tissues to malfunction, Germain says. That's why certain vaccines are especially recommended for people over 50 years of age.
Make better defenses
Researchers are still learning how to improve immune responses and vaccines. Some microbes are good at hiding from the immune system. Many avoid detection by mutating or changing so that previously exposed immune cells can no longer recognize them.
Dr. Shane Crotty of the La Jolla Institute for Immunology and his team are trying to take advantage of the way the body keeps up with these changes. They are studying a part of the adaptive immune system called the germinal centers. These are areas in the lymph nodes where immune cells develop and learn to make more effective antibodies. Germinal centers are formed temporarily in response to infection or vaccination. They don't just make antibodies against the germs that are in your body. They also make antibodies against different versions (variants) of those germs that you haven't been exposed to. Cells in the germinal centers are essentially guessing how the virus may change over time.
The germinal centers are one of the most amazing things your immune system does,” says Crotty. Take COVID vaccines as an example. COVID vaccines developed against the original virus caused people to produce antibodies that protected against other variants.
“All the antibodies that someone developed against other vaccine variants came from germinal centers,” explains Crotty.
The germinal centers can last in the body for up to six months. And the longer they are present, the more varied the antibodies they produce.
Crotty and his team are testing whether changing the way vaccines are given can help germinal centers last longer. Their recent study tested an experimental HIV vaccine on animals. The researchers administered the vaccine in many small doses over time. This produced antibodies that were more varied and lasted longer than those from the single large dose of vaccine.
As researchers continue to look for new ways to protect you from disease, keeping up with your vaccinations and living a healthy lifestyle are the best ways to boost your defenses.
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