Immunology and Immune System

- Overview

Immunology is the branch of biomedical sciences concerned with all aspects of the immune system in all multicellular organisms. A key component of staying healthy is the proper functioning of the immune system, a complex network of cellular processes and interactions that protect our bodies from foreign substances. 

The study of the immune system of living organisms is called immunology. This branch is very important to organisms because it covers defense mechanisms. You can watch as your immune system protects your body from many diseases and fights deadly infections. 

- Immunology

Immunology is the branch of medicine and biology that encompasses the medical study of the immune systems of humans, animals, plants, and intelligent species. From this we can see the difference between human immunology and comparative immunology in veterinary medicine and animal bioscience. 

Immunology measures, uses diagrams and differentiates the study of immunity at the cellular and molecular levels in a medical context, the immune system as part of the physiological level because it is so important for its function. Symptoms and diseases that occur in different states of health of both parties; immune system function and immune response, such as autoimmune diseases, allergic hypersensitivity, or in some cases immune system dysfunction, such as immune systemic disease or immunodeficiency, and specific transplant rejection) 

Immunology has applications in many medical disciplines, especially in the fields of rheumatology, virology, allergy (dermatology), bacteriology, oncology and further transplant medicine.

- The Immune System

In addition to structural and chemical barriers against pathogens, the immune system has two basic lines of defense: innate and adaptive immunity.

• Innate immunity is the first immune mechanism against invading pathogens. This is a rapid immune response, initiated within minutes or hours of being challenged, with no immune memory.
• On the other hand, adaptive immunity is antigen-dependent and antigen-specific. It possesses a memory that enables the host to mount a faster and more effective immune response upon subsequent exposure to an antigen.

There is a great deal of synergy between the adaptive immune system and its innate counterparts, and deficiencies in either system can trigger disease or disease, such as inappropriate inflammation, autoimmune disease, immunodeficiency disorders, and hypersensitivity.

- The Immune Response

The immune system protects the body against illness and infection that bacteria, viruses, fungi or parasites can cause. It is a collection of reactions and responses that the body makes to damaged cells or infection. So it is sometimes called the immune response.

Additionally, a strong immune system helps the body fight off HIV, cancer, malaria, dengue fever, and other diseases. Therefore, people with immune or autoimmune diseases should seek immediate help from an immunologist. In recent decades, scientists in the field of immunology have published research showing a direct link between immune system dysregulation and disease development. 

An excessive immune response can lead to conditions such as Crohn's disease or asthma. Autoimmune diseases, such as rheumatoid arthritis, in which the immune system cannot distinguish foreign cells from "self" cells can severely impact quality of life. 

The immune system is even now considered a major contributor to Alzheimer's disease pathology, with several studies exploring the impact of viral infection on the development of psychiatric symptoms.

- Proteins and The Immune System

The immune system is composed of a variety of different cell types and proteins. Each element performs a specific task aimed at recognizing and/or reacting against foreign material. 

The immune system is a wonderful collaboration between cells and proteins that work together to provide defense against infection. These cells and proteins do not form a single organ like the heart or liver. Instead, the immune system is dispersed throughout the body to provide rapid responses to infection. Cells travel through the bloodstream or in specialized vessels called lymphatics. Lymph nodes and the spleen provide structures that facilitate cell-to-cell communication. 

The bone marrow and thymus represent training grounds for two cells of the immune system (B-cells and T-cells, respectively). The development of all cells of the immune system begins in the bone marrow with a hematopoietic (blood-forming) stem cell. This cell is called a “stem” cell because all the other specialized cells arise from it. Because of its ability to generate an entire immune system, this is the cell that is most important in a bone marrow or hematopoietic stem cell transplant. It is related to embryonic stem cells, but is a distinct cell type. In most cases, development of one cell type is independent of the other cell types.

- The Immune System and Cancer

The immune system is important to people with cancer because: cancer can weaken the immune system; cancer treatments might weaken the immune system; the immune system may help to fight cancer.

Some cells of the immune system can recognize cancer cells as abnormal and kill them. But this may not be enough to get rid of a cancer altogether. Some treatments aim to use the immune system to fight cancer. 

Cancer and treatments can weaken immunity. Cancer can weaken the immune system by spreading to the bone marrow. The bone marrow produces blood cells that help fight infection. This most commonly occurs in leukemia or lymphoma, but can also occur in other cancers. Cancer can stop the bone marrow from making so many blood cells.

Certain cancer treatments temporarily weaken the immune system. This is because they cause the number of white blood cells produced in the bone marrow to drop. Cancer treatments that are more likely to weaken the immune system include: chemotherapy, targeted cancer drugs, radiation therapy, and high-dose steroids.

- Immune Deficiencies and Genetic Variations

Immune deficiencies can be caused by inherited or spontaneous gene variations, drugs that suppress the immune system, or infections that damage components of the immune system.

Alterations in a person's genes can cause the immune system to be deficient or have non-functional components. Most of these conditions are rare, but when they occur, a person is usually diagnosed early in life because they experience a higher-than-average number of infections. More than 40 different defects have been identified.

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- When the Immune System is Not Working Properly

Sometimes a person's immune system doesn't work as well. This can be caused by an immune deficiency that was present at birth; drugs that suppress the immune system, such as steroids; an unnecessary or excessive immune response, such as allergies; or an immune response to oneself, known as autoimmunity. One of the amazing aspects of the immune system is that it is compensatory, meaning that when one part is weak or non-functional, usually another can step in. 

Think of it like a trip to the grocery store. If you need to go to the store and you have a flat tire, you have other options for transportation - another motor vehicle, a bicycle, or walking. The substitute may or may not be as efficient, but it will still get you the job done. The same goes for the cells and proteins of our immune system. Most of the "jobs" of the immune system can be done by multiple parts of the immune system, although some parts are better at certain jobs than others.

The same features that make the immune system flexible also make research difficult. That's why studies will still need to be repeated in the lab or even in animals before we can be sure the findings apply. Laboratory and animal studies are still important, however, because they provide us with preliminary information that puts us in the best position to succeed when completing human studies.

- Unnecessary or Excessive Immune Response (eg, allergies)

When our immune system responds to a non-infectious substance, it can unnecessarily cause disease symptoms. Anaphylaxis is associated with this type of immune response. Likewise, sometimes our immune system overreacts and overwhelms our body, often leading to death.

Allergic reactions are closely related to a type of immune system cell called a mast cell. Mast cells are found in abundance under our skin and in the lining of our respiratory, digestive and reproductive tracts. Their main role is to protect us from parasites, but they are better known for their role in allergic reactions. 

When a mast cell is activated - whether by a parasite or, in the case of an allergic reaction, a non-infectious substance thought to be a pathogen—it releases a chemical called histamine. Histamine causes inflammation, recruits white blood cells to the area, increases mucus production and blood flow, and may also cause muscles to contract in an attempt to expel pathogens. 

Mast cells, which line the respiratory and digestive systems, are responsible for the muscle contractions that cause coughing, sneezing, vomiting, and diarrhea. Mast cells not only require pathogens, but also rely on binding to IgE or IgG antibodies to activate an immune response.

- Immune Responses against One’s Self (Autoimmunity)

Different aspects of autoimmunity can affect whether a person develops the disease.

Diseases caused by autoimmunity vary depending on where in the body the faulty immune response is targeted. In some cases, only one organ is affected, such as type 1 diabetes that affects the pancreas. In other cases, however, the immune response targets one protein or part of the body rather than being localized, leading to widespread symptoms, such as in rheumatoid arthritis.

Autoimmunity also becomes important in the context of blood transfusions, tissue transplants and organ transplants. In these cases, doctors and scientists need to find ways to trick a person's immune system if the tissues don't come from the person who received them. If the immune system is activated, it attacks foreign tissue. This is called rejection. Rejection can lead to new, often chronic symptoms.

- Research Topics in Immunology

• Adaptive immunity
• Antigen processing and presentation
• Antimicrobial responses
• Applied immunology
• Autoimmunity
• Bone marrow transplantation
• Cell death and immune response
• Chemokines
• Coagulation system
• Complement cascade
• Cytokines
• Gene regulation in immune cells
• Haematopoiesis
• Imaging the immune system
• Immune cell death
• Immune evasion
• Immunogenetics
• Immunological disorders
• Immunotherapy
• Infection
• Infectious diseases
• Inflammation
• Innate immune cells
• Innate immunity
• Lymphatic system
• Lymphocytes
• Lymphoid tissues
• Mucosal immunology
• Neuroimmunology
• Osteoimmunology
• Plant immunology
• Signal transduction
• Translational immunology
• Transplant immunology
• Tumour immunology
• Vaccines
• Etc.

[More to come ...]