immunology 101

This past year has been unlike any other, and sadly it seems as though we're still not close to what life was like just a little over a year ago. What's even worse is that nobody seems to truly know what's going on. Everyone has their own opinions, including those in the government telling us how things are supposed to be now, so what is considered to be guidance is really just seen as doctors and politicians pushing their own political narrative. Knowledge is crucial to have right now because it can help you to think critically, clearly, and with common sense instead of just blindly following every word of the mainstream media.

I rarely talk about sciency things on here which is crazy because science is such a big part of my life as a Biology student. It's especially crazy because so many of the most controversial topics right now are centered around scientific truth and the basics of biology that have been ingrained in my mind over the past three years. Are men and women different? Should transgender girls be allowed to play in female sports? Is an unborn baby considered to be life by biological standards? Does science contradict Christianity? Do we exist because of evolution or because we were created? (That one might not be as hotly debated as the rest of these, but it's an especially fun one for me because it involves two of my favorite topics to learn about: science and Christianity. And yes, I do realize how much of a nerd that sentence made me sound like haha.). And most prevalent to our current circumstances: what are viruses? how do viruses spread and infect people? should we trust science? what is our immune system? and how do vaccines work/ what even are vaccines in the first place? So those are the topics I'm going to talk about today. 

A huge part of the reason why I love science is because it might be the closest I'll ever get to understanding God and the way He works. Trust me, no amount of science will ever fully explain God, nor will it even explain the nature of this planet. But what it does do is show me just how powerful and great He really is. Whenever I just sit back and think about all of the tiny details hidden inside our bodies and out there in the expanses of nature, I am just mind blown at how intricate the natural world is. To some, science is the reason they don't believe in God. But to me, science is the biggest piece of evidence for His existence. There is no way this world could be so intricate, with all the tiny details perfectly tuned for viability, if it was all created by chance. But let's get back to immunology, which is why I went on that tangent in the first place. The immune system is one of those things that fascinates me. There is so much detail to it, but each small detail serves a huge purpose. A lot can go wrong when even just one thing is out of place, doesn't work correctly, or is hindered by a pathogen. I will spare you all of those details. Trust me when I say that you do not want to learn about all of them. I experienced that first hand in my Immunology class this past semester. You really only need to understand the basics anyway to get a good feel for how the immune system works, and how strong and effective it really is. I'm going to give you some important definitions that I think are important to understand the immune system and to be able to navigate all of the information being thrown at us about this subject currently, and then we'll start with the basics of the basics. 

Key Terms in Understanding the Immune System: 

immunity- state of protection from infectious disease

vaccine- weakened strain of disease pathogen given with the goal of producing active immunity and eventually a memory response during future encounters

herd immunity- a critical number of people acquires protective immunity against a pathogen and acts as a buffer for the rest of the population 

humoral immunity- host defenses that are controlled by antibodies present in the plasma, lymph, and tissue fluids

antibody- immunoglobulin proteins that recognize foreign antigen and facilitates clearance of that antigen

passive immunity- temporary adaptive immunity conferred by the transfer of immune products, such as antibody, from an immune individual to a nonimmune one

active immunity- adaptive immunity that is induced by natural exposure to a pathogen or by vaccination

cell-mediated immunity- host defenses that are mediated by antigen-specific T cells

antigen- any substance that elicits a specific response by B or T lymphocytes

pathogen- organisms causing disease

innate immunity- includes built-in molecular and cellular mechanisms that are evolutionarily primitive and aimed at preventing infection or quickly eliminating common invaders

adaptive immunity- host defenses that are mediated by B cells and T cells following exposure to antigen; exhibit specificity, diversity, memory, and self-nonself discernment

immunologic memory- ability of the immune system to respond much more swiftly and with greater efficiency during a second exposure to the same pathogen

primary response- during a first encounter with a foreign antigen, key lymphocytes that will be used to eradicate the pathogen are clonally selected, honed, and enlisted to resolve infection

secondary response- memory cells trained during the primary response are re-enlisted to fight again; happens almost immediately upon exposure

Now let's get into the immune system and its response to pathogens.

Innate Immune Response- The First Line of Defense

An immune response is not activated until the immune system is exposed to the pathogen. Exposure occurs when the pathogen enters the body through a physical or chemical barrier. These barriers are the primary components of the innate immune system as well as several defense mechanisms and immune responses. This part of the immune system is inherited from your parents and is built into your body to allow rapid recognition and destruction of pathogens. 

Physical barriers include things like skin, the GI tract, the respiratory tract, eyelashes, and body hair. If the pathogen gets through these barriers, then the innate immune system has several defense mechanisms to try to flush the pathogen out of the body before infection occurs. These things include secretions, mucous, bile, gastric acid, saliva, tears, and sweat. If all of these barriers fail and the pathogen enters the body, general immune responses occur. The usual response of the innate immune system is inflammation caused by the swarming of many innate cells to the site of infection. 

Just a quick side note- the innate immune system is very general and nonspecific. It doesn't know what the pathogen is that just entered the body, it's just trying to get it out. Anything that is identified as foreign (non-self) is a target for the innate immune response. This could be a virus, bacteria, parasite, allergen, etc. This part of the immune system is solely engaged by the presence of antigens. 

If these antigens are able to pass through the physical barriers, then the innate immune response recruits certain immune cells to try to kill the pathogen before it can do too much damage to the body. These include:

• phagocytes- circulate the body looking for potential threats to engulf and kill
• macrophages- macrophages are a type of phagocyte, so they ingest and destroy pathogens as well. They can also release cytokines that signal and recruit other cells to the area of infection
• mast cells- found in mucous membranes. When activated, they release cytokines that contain chemical molecules to create an inflammatory cascade. These cytokines act as messengers, alerting other immune cells that there is an infection, so they are either alert and on the look out, or so they can come help at the primary infection site.
• neutrophils- phagocytic white blood cells that contain granules. These granules cause bacteria and fungi to stop reproducing and die upon contact. 
• eosinophil- granulocytic white blood cells that target multicellular parasites. They secrete a range of highly toxic proteins that kill bacteria and parasites. Their release is highly regulated, though, because the toxins it releases can also cause tissue damage during allergic responses. 
• basophils- granulocytic white blood cell that release histamine during an allergic response.
• natural killer (NK) cells- destroy infected host cells to stop the spread of an infection. 
• dendritic cells- present antigen to other parts of the immune system, specifically to T cells that trigger the adaptive immune response to begin. 

Adaptive Immunity- The Second Line of Defense 

Once antigen is presented to the T cells by antigen-presenting cells like dendritic cells, the adaptive immune response begins. This part is way more specific than the innate response because it forms a specialized response to each specific antigen. These responses get more efficient and effective after each exposure to the pathogen, but we'll talk more about that later. Like the innate immune system, the adaptive immune system uses several cells to form its response.

• t cells- mature in the thymus (lymphoid organ located in the neck). These cells express T cell receptors that bind to antigen so the T cell can present the antigen to the B cells which carry out the adaptive immune response by creating antibodies. The T cells also express other receptors- either CD4 or CD8. Those that express CD4 are considered to be T helper cells and help to activate cytotoxic T cells which are the T cells that express CD8. Cytotoxic T cells are responsible for removing pathogens and infected host cells, usually by killing them. 
• b cells- form and mature in the bone marrow. Naive B cells (those that haven't yet been exposed to antigen) enter the lymphatic system to circulate throughout the body. B cells encounter antigen in the lymph nodes which triggers their final stages of maturation. After they finish maturing, they proliferate into many different subtypes of B cells, some of which include plasma cells which produce the antibodies that bind directly to antigen so it is recognized as foreign and expelled from the body, or they form memory B cells. Memory B cells remember the pathogen and produce the same antibodies for this pathogen as the plasma B cell. The memory response is activated whenever the body is exposed to the same pathogen more than once. 

Memory Response

Immunological memory generally lasts a lifetime even if the antibodies themselves only last a little while after the first infection. This is because the memory B cells are stored in various places throughout the lymphatic and immune systems so they can be activated upon a second (or third or fourth or fifth) exposure almost immediately. These B cells remember the specifics of an antigen so the process is sped up more and more with each sequential exposure. Depending on the person and the strength of their immune system, the memory response could act so quickly and effectively that the antigen is expelled from the body before they even have symptoms, meaning they may never even know they were infected in the first place. This is also the case because the memory response is always activated before naive lymphocytes (those that have yet to be exposed to antigen) are activated for the primary adaptive response to take place again. The only way the adaptive immune response would be activated again for that same pathogen was if the pathogen evolved in some way that made it appear differently to the immune system. In many cases, especially with viruses, this happens by a change in the proteins on the pathogens surface. In viruses, these surface proteins are called spike proteins, a term you've probably heard used in the talks surrounding covid. 

Vaccines

The goal of a vaccine is to create an active immune response that will create antibodies against the foreign antigen, and therefore create a memory response that will be ready to fight off the infection after another exposure to the same pathogen (or in this case to the real pathogen) in the future. This process is called immunization- the process of eliciting a state of protective immunity against a disease-causing pathogen. Vaccination is an event; immunization is a potential outcome of that event. However, immunization can also be achieved through exposure to the live pathogen followed by recovery. Because of this, there is really no need to get a vaccine against a pathogen that you've already been infected by. This is especially the case because natural exposure creates a more robust immune response than vaccination would, meaning it would most likely be stronger and more effective. I've also heard a few doctors recently say that getting the covid vaccine after already being infected by SARS-CoV2 increases your chances of having adverse reactions to the vaccine. I'm not sure how well that has been studied, but it's definitely something to consider, especially since you would already have generated memory cells through natural exposure. 

Vaccines must be safe, effective in preventing infection, and reasonably achievable for the given population. In order to ensure this, vaccines go through various phases of testing once it has been proven to be successful in animal models. 

• phase I- assesses human safety
• phase II- tests effectiveness against the pathogen
• phase III- volunteer populations are given the vaccine to observe natural evidence of protection over time
• phase IV- monitor safety, effectiveness, and long-term impact

*because the covid vaccine was manufactured so quickly and was only approved for emergency authorized use, we are still only just getting through phase III and beginning phase IV. It was not known whether or not the vaccine would work in decreasing cases in vivo (scientific term that basically means in real life vs. "in vitro" which basically means in a lab setting). It was also not known, and still really isn't, whether or not protection will persist over time or if booster shots will be needed at various points throughout the vaccinated persons life. What is especially unknown right now is what the long-term impact and safety concerns are. Because the focus of phase IV is on the long-term, this phase could last many more years until it is determined what the long-term safety, effectiveness, and impact is down the road. 

There are several different types of vaccines currently available.

• live attenuated vaccines- these vaccines contain parts of the pathogen that are attenuated (weakened) in a lab so they can provide exposure to the "real thing" without risking serious infection. Advantages of this type of vaccine are that the attenuated pathogen closely mimics the growth patterns of the real pathogen which improves immunogenicity and results in more efficient production of memory cells, and it only requires a single dose. Disadvantages include the ability for the attenuated pathogen to mutate into a more virulent and harmful form, and that they can be associated with similar complications to what would have occurred from natural infection. Vaccines of this type are available for measles, mumps, and rubella (MMR); rotavirus; smallpox; chickenpox; and yellow fever.
• inactivated/"killed" vaccines- pathogens are used in this vaccine after being killed with heat or chemicals to prevent their ability to replicate inside the host. These are generally safer than live attenuated vaccines, but they do still pose a risk of infection, and they often require repeated boosters to maintain long lasting protection. Vaccines of this type are available for hepatitis a; flu; polio; and rabies.
• subunit vaccines- specific, purified macromolecules derived from the pathogen are used in these vaccines to create an immune response. This type of vaccines is available for Hib (hemophilus influenza type b); hepatitis b; human papillomavirus (HPV); pertussis (whooping cough); pneumococcal disease; meningococcal disease; and shingles.
• recombinant vector vaccines- reproduce a live virus that has been engineered to carry extra genes from the pathogen that is infecting the body. They work as a natural infection and train the immune system to recognize and attack antigens. 
• mRNA vaccines- RNA is the molecule that signals for the production of the proteins that make up our body. This type of vaccine triggers an immune response by signaling for the protein that would create that immune response. Since these are so new, I don't know a ton about them. Maybe I'll do more some more research and make a whole post just on mRNA vaccines.

Tips to Improve Your Immune System

• eating a healthy diet, particularly one that is high in fruits and veggies
• eat garlic- contains the compound allicin which is well-known for its ability to boost the immune system 
• take supplements or eat good sources of prebiotics and probiotics to support the gut microbiome which protects against infection
• exercise regularly 
• maintain a healthy weight 
• limit sugar 
• eat healthy fats to reduce inflammation in the body; chronic inflammation can suppress the immune system (and also- sort of related but not really- provides a good environment for tumor cells to thrive and reproduce. just another reason to reduce inflammation in the body)
• water. water. water.
• get a good amount of good quality sleep
• wash your hands, have good hygiene, cover your nose and mouth when you sneeze and cough (you know, all the stuff we learned in kindergarten) to prevent infection 
• minimize stress
• take supplements to get good levels of vitamins A, C, D, and E, and zinc, selenium, elderberry, and garlic. 
• get outside, breathe in fresh air, and take in the sunshine. 
• consume a lot of antioxidants- berries, carrots and spinach, or Young Living’s Ningxia drink which is made from wolfberries (one of the best sources of antioxidants in nature)
• diffusing essential oils like eucalyptus, tea tree, lavender, lemon, and thieves which all have antimicrobial, antiviral, and cleansing properties 
• cleaning with lemon and thieves essential oils for the same reasons I listed above for diffusing them

I always love to learn about new things, but learning about things that are very prevalent and important in today’s culture has been something God has been laying on my heart to do recently. It’s so important to learn things for yourself before you form an opinion on something instead of forming your opinion from other people's opinions. The opinions of others are biased and can be deceiving, but the facts are the truth. They’re not biased. They’re not trying to get you to agree with them. They’re just there for us to learn about, observe, and interpret. So many people get their information from social media, which can at times be good depending on who you are listening to/watching, but for the most part it's just not a good idea. So many people on social media are just talking about their opinions even though they've done no real research to back those opinions up. The majority of people on social media have no idea what they're talking about. I'm not saying that to be rude, its just the truth. Our society needs to start doing research for themselves instead of taking others words for things, or this country will fail miserably. 

I think that part of the reason why God has been leading me to learn more things for myself about so that I better understand those topics so I can form good stances myself, and will have a good understanding in order to back up my stance if someone attacks it (which is bound to happen in this day and age because cancel culture is very real). But I also think He wants me to share these truths, sometimes even hard truths, with others. Part of loving others is telling them the truth, especially when it’s not the popular, mainstream idea. I would never want someone to just leave me to believe the lies the world is pushing down my throat. I really hope if that were the case that someone would lovingly explain to me the reality of the situation and the facts that make their claim reality. Reality isn’t always easy to accept because a lot of times it doesn’t feel good. But we have to accept it if we are going to get anywhere as a society. I’m really excited to do more reading and listening over the summer about things like politics, economics, government, history, science, and religion- basically all of the things that are very controversial to talk about right now- and share with you all what I learn in hopes that you can also form a solid view on those issues from that information. 

With Love,