A healthy immune system is not fighting every minute. It's also deciding what not to react to, what not to kill; this discernment is a skill it spends our whole lives refining. The immune system's job, said Petter Brodin, an immunologist at the Karolinska Institute in Sweden, is to maintain a healthy relationship with all of the bugs that live in, on, and around us.
The thing is, the immune system is very complicated. Arguably the most complex part of the human body outside the brain, it’s an absurdly intricate network of cells and molecules that protect us from dangerous viruses and other microbes
When the innate response fails to fend off an invasion, the invaders are handled by adaptive immunity. Instead of broad patterns, each adaptive cell sees a very specific pattern. This could be one particular protein on the surface of a virus or bacteria.
But because the adaptive immune system doesn’t know what invaders it may meet, it makes millions of different cells, each of which is created to recognise a random different pattern. One adaptive cell may recognise only the flu virus, for instance, while another may recognise only a single type of bacteria.
As we age, the immune system begins to shift into a heightened state of alert, dialing up inflammation and running out of certain immune cells.
Only recently have researchers come to realize that one of the major defenses against infection, especially in the gut, but also elsewhere, is mediated by a family of innate immune cells known as innate lymphoid cells (ILCs). In this series, we focus on one particular subset of this family, group 3 innate lymphoid cells (ILC3s), which have some remarkable and unexpected properties.
Organisms must constantly protect themselves from harm caused by pathogens like viruses and bacteria. The immune system delivers this protection via numerous pathways. The immune response is broken down into innate immunity, which an organism is born with, and adaptive immunity, which an organism acquires following disease exposure.
The immune system is made up of two parts: the innate, (general) immune system and the adaptive (specialized) immune system. These two systems work closely together and take on different tasks.
Human beings are born pretty helpless, with a lot of developing to do. And just as you must learn such skills as how to walk, so must your immune system learn to defend against infections. As time passes, your immune system matures through different stages, much the way you advanced from crawling to standing, walking and running.
Antibodies are great and all, but macrophages, B cells, and helper T cells deserve some attention too.