How Our Immune System Works?

The immune response works in phase; it’s all about amplification of an initial signal and spreading that message as quickly as possible to “round up the troops” when danger is present. The response starts with nonspecific, non-induced responses but quickly switches to more broadly specific, induced responses and then to specific acquired responses, which allows for a full responses and then to specific acquired responses, which allows for a full response, though it can take as much as five days to get to the later stage. Now, Let’s get into deep.

Establishing surface barriers and mucosal immunity

The first line of defense is a good barrier system. As the old saying goes, “Good fences make good neighbors”, if the virus or bacteria never make it into your body, that’s a good thing. So simple barriers, such as skin, protect you. But what about all those parts of the human body that are exposed to the outside world that are not covered by skin? Where can bugs get in? Well, you can breath them in, or they can come in on food you eat, and women also can be exposed through vaginal contact. So at each of these places, you have a series of defenses called lymphoid tissue, and each one is named to reflect the area it’s protecting. Lymphoid tissue is where all the cells of the immune system hang out, waiting to go work.

  • NALT (Nasopharyngeal associated lymphoid tissue): Tonsils and adenoids plus the upper respiratory mucosa ( cells lining the airways)
  • BALT (Bronchi- associated lymphoid tissue): Lower respiratory mucosa and bronchial patches
  • SALT (Skin- associated lymphoid tissue): All the lymph tissue under and part of the skin
  • GALT (Gut- associated lymphoid tissue): Includes intestinal mucosa, Peyer’s patches, and the appendix
  • MALT (Mucosa- associated lymphoid tissue): Includes all the other categories plus urogenital/ vaginal lymphoid tissue (VALT)

Accepting normal flora

Ever stop to think about how many bacteria live in and on you? They are everywhere – your skin, your nose, your gut (especially your gut!), In fact, you have more individual bacteria in you than cells of you! Kind of makes you wonder who is in charge here, right?

However, all those normal bacteria help keep things in check. Your immune system has learned that these bacteria aren’t the enemy and don’t pose a threat, so it lets them hang around. In turn, they help keep things in balance, especially in the gut. If you have ever had to take antibiotics for an infection and then developed diarrhea afterward, you understand the importance of normal bacteria- the antibiotics killed off some of the good guys as well as the bad guys as well as the bad guys, and the usual balance got disturbed. The good news is that it can fix itself pretty quickly.

Complement system

The complement system is also important in the immune response. It consists of various proteins produced by the liver that flow through the bloodstream in inactive form. When the proteins encounter an infection, they become activated and cause an inflammatory response. These proteins have the ability to launch a rapid cascade of reactions to stimulate other complement molecules, hastening the inflammatory response rapidly. The activity of these proteins not only kills invaders but also marks them for easier recognition by other cells in the immune system.

Innate Immunity

The innate immune response refers to the stuff you are born with. The innate system kicks in first, during the first 96 hours or so after infection by a virus or bacteria. Initially, structural issues respond in a nonspecific, non-induced way, such as by trying to flush out the invader in saliva or respiratory mucus. The innate system also includes all those cilia that line the respiratory tract; the little hair- like organs that move particles back out if you breathed them in. Also part of this structural system is your reflex to cough things back out, and if something you ate is particularly a problem, you will vomit it back up.

After this first nonspecific response comes a broadly specific, induced response from your immune cells. When a pathogen is encountered, dendritic cells and macrophages move in to eat it up. Polymorphonuclear leukocytes also can move in and engulf the invader, breaking it down into pieces. If a virus or cancer cell is encountered, usually the killer T cells do the job. All these cell responses are general and “reflex” in nature.

The amazing thing is how fast these signal get amplified and sent to the rest of the immune system; it takes only a day or so! This happens so fast because the immune system triggers NF-kB (nuclear factor kappa- light- chain- chain- enhancer of activated B cells) an other transcription factors. NF-kB is protein that stimulates the production of some of the proteins that make up antibodies. It plays an important role in regulating the immune response; when it goes haywire, the body gets weird messages so that cancer and autoimmune conditions may develop. when the transcription factors are activated, they cause production of inflammatory cytokines, free radicals, and eicosanoids, all of which produce a controlled inflammatory condition.

Acquired immune response

After the innate response kicks in, the acquired response begins. These two responses function together, though through different pathways. The acquired immune response varies from person to person because it depends on the invaders each individual is from person to person because it depends on the invader each individual is exposed to. Although the process is the same, the actual antibodies vary. After the dendrites and macrophages have eaten up the invader, they take parts of that invader and present them on the surface of the dendrite. This action, called antigen presentation, shows the rest of the immune system what the invaders look like.

This antigen presentation stimulates helper T cells and cytolytic T cells to come into the area to help fight off the invader. It also stimulates B cells to make antibodies. These antibodies help mark the invader so other cells find it more easily; they also bind particles of the invader together to “corral” them and make them easier to fight. This whole process takes a while, usually four to five days. That explains why the typical viral infection takes nearly a week to resolve –when your immune system is working as well as you want it to.

T cells randomly make as many receptors as they can to be ready for anything. Sometimes, that means they make receptors for something that’s actually “self”. These cells het deleted either by “supervisor” cells in the thymus, or by regulatory T cells out in the peripheral blood. If they somehow escape this deletion process and happen to replicate, it can cause an autoimmune response.

Cell mediated immunity, humoral immunity, and cytokines

Cytokines are proteins that are part of cellular communication; in this case, we are specifically referring to immunomodulating agents that are part of proliferating the immune response. Helper T cells create two categories of cytokines: Th1 cytokines are involved in cell mediated immunity and delayed sensitivity, and Th2 cytokines are part of humoral immunity and the allergic response. Th2 cytokines promote cell growth and recruit mast cells, basophils, eosinophils, and B cells to the area.

The body needs to have a balance of these two categories of cytokines. Otherwise, you run the risk of either having too much inflammation or too little inflammation (the whole system isn’t working), or you start creating a response to yourself, which is an autoimmune disease. Different specific cytokines can be measured in the bloodstream, so healthcare providers can try to figure out what exactly your immune system is doing when it’s acting up. For example, TNF- alpha and IL-17 (tumor necrosis factor alpha and interleukin 17) are both specific markers of inflammation. The levels of these two markers start to rise long before most of the symptoms of an inflammatory condition really get started. A smart practitioner who see signs of impending trouble or notices genetic predisposition to an inflammatory state can measure these levels and then, if they are elevated, take steps to normalize them before they cause damage.

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