Immunology is a branch of biology that studies the immune system, its components, physiological functioning, types, and disorders in all organisms. It explores the intricacies of the immune system, which serves as our body’s defense mechanism against pathogens and foreign substances. In all aspects of medicine, a comprehensive understanding of immunology is crucial for delivering optimal patient care. Understanding immunology helps healthcare professionals diagnose and treat the disorders associated with the immune system effectively, often using targeted therapies that aim to regulate the immune response. Immunology in humans has various examples in real life that impact human health and well-being. Read on to learn about immunology examples in real life.
Vaccines, also known as shots, are one of the most effective forms of introducing passive immunity. It includes the introduction of weakened forms of microbes into the body, prompting the immune system to learn how to counteract these foreign substances. Consequently, if encountered again, the immune system can swiftly neutralize them, protecting against diseases such as influenza and measles.
In response to infection or inflammation, the body might raise its internal temperature, resulting in fever. Elevated body temperature can enhance the immune response by promoting the activity of immune cells and inhibiting the growth of some pathogens.
Allergies occur when the immune system reacts excessively to benign substances, such as pollen, dust, or pet dander. This reaction triggers symptoms like sneezing, runny nose, watery eyes, and itching due to the immune system mistakenly identifying these substances as threats.
4. Cancer treatment
Immune system-based cancer treatments involve instructing the immune system to recognize and combat cancer cells. Therapies such as immune checkpoint inhibitors help immune cells identify these abnormal cells, therefore impeding the cancer’s progression.
5. Autoimmune disorders
Autoimmune disorders are conditions in which the immune system mistakenly targets and attacks the body’s own tissues, organs, or cells as if they were foreign invaders. In a healthy immune system, immune cells recognize the difference between “self” and “non-self” substances, but in autoimmune disorders, this recognition breaks down, leading to an immune response against the body’s own components. The exact causes of autoimmune disorders are not fully understood, but they are believed to result from a combination of genetic predisposition and environmental triggers. Treatment approaches may include immunosuppressive medications, anti-inflammatory drugs, and therapies that help regulate the immune response. Numerous autoimmune disorders affect specific parts of the body. Some examples include:
- Type I diabetes
Type I diabetes is caused by the immune system attacking and destroying insulin-producing beta cells in the pancreas. Type II diabetes is mainly caused by obesity, while Type I diabetes is an autoimmune disease. In Type I diabetes, without sufficient insulin, sugar levels in the blood rise, leading to various symptoms such as excessive thirst, frequent urination, unplanned weight loss, and fatigue. Individuals affected with type I diabetes require lifelong insulin shots to manage their blood sugar levels.
- Celiac disease
It is triggered by an immune response to gluten, a protein found in wheat, barley, and rye. Immune cells damage the lining of the small intestine, leading to malabsorption of nutrients. Symptoms can include digestive issues like diarrhoea, abdominal pain, fatigue, weight loss, skin rashes, and bloating. Individuals with Celiac disease are also prone to other autoimmune diseases such as Type I diabetes, lactose intolerance, rheumatoid arthritis, intestinal cancer, and thyroid disease.
- Rheumatoid arthritis
It is a chronic autoimmune disorder that primarily affects the joints. The immune system mistakenly targets the lining of the joints (synovium) and causes inflammation. This leads to pain, swelling, stiffness, and potential joint damage over time. Rheumatoid arthritis affects the knees, wrists, and other organs, causing complications such as lung inflammation, rheumatoid nodules, and heart problems.
- Hashimoto’s Thyroiditis
It primarily affects the thyroid gland leading to inflammation and impaired thyroid function. Immune cells attack the thyroid tissue and result in hypothyroidism, causing symptoms such as fatigue, weight gain, cold intolerance, and depression.
- Pernicious Anaemia
It is a type of Vitamin B12 anaemia that occurs when the immune system attacks stomach cells responsible for producing intrinsic factors, a substance needed to absorb vitamin B12. Without intrinsic factors, the body cannot absorb enough vitamin B12 from the diet, leading to a low red blood cell count (anaemia). It can potentially cause neurological symptoms such as numbness and weakness. The symptoms can be alleviated via treatment involving Vitamin B12 supplementation.
- Addison disease
It is an autoimmune disease where the immune system attacks and damages the adrenal glands, leading to insufficient production of essential hormones like cortisol and aldosterone. This results in symptoms such as fatigue, weight loss, low blood pressure, and electrolyte imbalances. Treatment involves hormone replacement therapy to manage symptoms and maintain hormonal balance.
- Graves disease
Grave’s disease is an autoimmune disorder causing an overactive thyroid gland (hyperthyroidism). The immune system mistakenly stimulates the thyroid gland and leads to excess production of thyroid hormones, causing symptoms such as anxiety, rapid heartbeat, weight loss despite increased appetite, bulging eyes, tremors in hands, etc. Hyperthyroidism cannot be prevented but can be treated. Treatment includes medications to regulate thyroid function, radioactive iodine therapy, or surgery to remove some part of the thyroid gland.
- Multiple sclerosis
Multiple sclerosis affects the central nervous system, including the brain and spinal cord. It occurs when the immune cells target the protective covering of nerve fibres (myelin sheath), causing inflammation and damage. This disrupts the communication between nerve cells, leading to a wide range of symptoms, such as fatigue, muscle weakness, numbness, coordination problems, and cognitive difficulties.
This autoimmune disease is characterized by rapid skin cell growth. Immune cells mistakenly trigger the skin cells to reproduce too quickly, leading to the formation of thick, scaly, and inflamed patches of skin. These patches can be itchy and painful, and they often appear on the elbows, knees, scalp, and lower back.
- Systemic lupus erythematosus (SLE)
SLE is a complex autoimmune disorder that can affect multiple organs and tissues. Immune cells produce antibodies that target various components of the body, including DNA and proteins. Symptoms can vary widely and may include fatigue, joint pain, skin rashes (especially a ‘butterfly’ rash on the face), fever, and organ damage, affecting the kidneys, heart, lungs, and brain.
6. Immunodeficiency disorder
Immunodeficiency disorders are conditions where the immune system’s ability to fight infections and diseases is compromised. These disorders can be inherited or acquired, leading to reduced or absent immune responses. As a result, individuals with immunodeficiency disorders are more susceptible to infections and might experience severe or recurrent illnesses. Treatment may involve immunity-boosting therapies, medications, and preventive measures to manage infections. Some examples include:
The human immunodeficiency virus (HIV) attacks the immune system, specifically CD4 T cells, which weakens the body’s ability to fight infections and diseases.
- Common Variable Immunodeficiency (CVID)
It is characterized by low levels of antibodies which leads to recurrent infections. An infected individual has repeated infections in the ear, respiratory system, and sinuses. Common symptoms of Common Variable Immunodeficiency include chronic cough, difficulty in breathing, and weight loss.
A lack of essential nutrients can weaken the immune system, making individuals more susceptible to infections. Common symptoms include fatigue, dizziness, and weight loss.
- Cancer treatments
Recommended treatments for cancer such as chemotherapy and radiation therapy can suppress the immune system, leaving individuals vulnerable to infections.
- Autoimmune Lymphoproliferative Syndrome (ALPS)
It is a rare genetic disorder where the immune system fails to regulate the number of lymphocytes, leading to an increased risk of autoimmune diseases and lymphoma.
COVID-19 is a contagious respiratory illness caused by the SARS-CoV-2 virus (infamously known as coronavirus). The virus primarily spreads through respiratory droplets from infected individuals. Symptoms vary widely, ranging from mild, flu-like symptoms such as fever, cough, and fatigue, to severe symptoms like chest pain, difficulty breathing, and loss of taste or smell. Some infected individuals may remain asymptomatic but potential carriers of coronavirus. The treatment of COVID-19 depends on the severity of the symptoms. Mild cases often require rest, hydration, and over-the-counter medications to manage symptoms. Severe cases, especially those with respiratory distress, may require hospitalization, supplemental oxygen, and antiviral medications. Vaccination plays a crucial role in preventing severe illness by stimulating the immune system to recognize and fight the virus. Preventive health measures, such as practicing social distancing, wearing masks, and sanitizing hands, also aid in limiting the spread of coronavirus.
8. Social immunity in honeybees
Honeybees exhibit a form of social immunity within their colonies. When a bee encounters a larva infected with a pathogen, it releases a signalling pheromone to alert other bees. These bees then collectively remove the parasitized larva from the hive, preventing the spread of disease. This kind of animal behaviour shows how bees utilize social interaction to protect the entire colony from infections.
9. Cancer immunity in elephants
In the scientific community, elephants are known for their extremely low cancer rates compared to their large body size. This is due to them having extra copies of a tumor-suppressing gene, p53. Despite their large size, elephants have a decreased cancer risk due to extra evolved tumor suppressor gene LIF6 (Leukemia Inhibitory Factor). As soon as an abnormality is detected, p53 is upregulated and induces cell death (apoptosis). These additional number of p53 gene copies increase their efficiency of repairing damaged DNA, reducing the risk of uncontrolled cell growth and cancer development. Studying this unique immune mechanism in elephants could provide insights into cancer resistance in humans.
10. Antimicrobial peptides in frogs
Frogs secrete small proteins called antimicrobial peptides as a physical and chemical barrier against disease-causing microorganisms (pathogens). These peptides exhibit broad-spectrum activity against bacteria, fungi, and viruses and thus could inspire the development of new antimicrobial treatments to combat drug-resistant pathogens.
11. Natural antibodies in sharks
Sharks are known to possess a robust immune system producing natural antibodies called immunoglobulin new antigen receptors (IgNARs). These antibodies are smaller and more stable than those in mammals, making them effective in binding to a wide range of antigens. Shark’s immune system has applications in medical research, including the development of therapeutic antibodies for human diseases.
12. Immunity in plants
Many plant species possess unique defense mechanisms to protect themselves against pathogens and maintain their health. Tomato and rice species have pattern recognition receptors (PRRs) on their cell surfaces that can detect pathogen-associated molecular patterns (PAMPs) and further activate pathogen-triggered immunity (PTI). Other examples of plant immunity are seen in some species of potato and wheat which possess resistance proteins that can identify specific pathogen effectors and initiate effector-triggered immunity (ETI). ETI then activates a hypersensitive response, resulting in localized cell death which checks pathogen proliferation. These defence mechanisms not only ensure plant survival but also inspire innovations in agricultural practices and crop protection strategies.
13. Flow cytometry
Flow cytometry is a significant technique in immunology, enabling detailed analysis of immune cell characteristics, functions, and responses. It plays a multifaceted role in immunological research and diagnostics. Through fluorescently labelled antibodies, it identifies and quantifies various immune cell types, facilitating a comprehensive understanding of immune cell populations. One of its key applications called immunophenotyping, pinpoints T cells and B cells and goes beyond identification and functional analysis. Researchers can assess cellular responses by detecting cytokine production and evaluating immune cell health, viability, and apoptosis. Flow cytometry also sheds light on cell proliferation and study immune cell activation and their reactions to stimuli. In clinical contexts, flow cytometry diagnoses immune disorders and tracks treatment responses by analyzing immune cell counts and functionality.
14. Genetic sequencing tools
Genetic sequencing tools play a significant role in immunology by enabling the analysis of genes and genomes of immune cells, pathogens, and individuals. These tools allow researchers to unravel the genetic basis of immune responses, identify specific genes involved in immunity, and uncover genetic variations linked to immune-related disorders. Some of the examples are as follows:
- Next-generation sequencing (NGS)
Technologies like Illumina and Ion Torrent provide high-throughput sequencing (sequencing of many fragments of nucleotides at the same time). They facilitate genome-wide studies (studying the genome of a large group of people to search small variations called SNPs), identifying genes that regulate immune responses, immune cell differentiation (lymphocytes), and immune-related pathways.
- Single-cell sequencing
Techniques like single-cell RNA sequencing reveal the gene expression profiles of individual immune cells. This helps identify rare immune cell types (regulatory T cells), trace cell development pathways, and understand cellular heterogeneity within tissues.
- HLA typing
Genetic sequencing tools aid in Human Leukocyte Antigen (HLA) typing which is crucial for organ transplantation and understanding autoimmune diseases where HLA genes play a role.
- Pathogen sequencing
By sequencing the genomes of pathogens, immunologists can track pathogen evolution, understand the mechanisms of immune evasion, and develop targeted treatments or vaccines.
- Evolutionary studies
Comparative genomics and phylogenetic analysis of immune-related genes provide insights into the evolutionary history of immune responses across species.
- Personalized medicine
Genetic sequencing assists in identifying genetic variants involved with immune-related disorders, allowing personalized treatment approaches based on an individual’s genetic makeup.
15. Nuclear transfer technology
Nuclear transfer technology is also known as somatic cell nuclear transfer (SCNT). It has diverse immunological applications for studying immune cell development, epigenetic modifications, and immune responses. By transferring cell nuclei into egg cells, immunologists observe how nuclei influence cell differentiation. SCNT also aids in exploring the role of epigenetics in immune cell behaviour and investigating immune tolerance mechanisms. It contributes significantly to immune cell function, genetic factors, and regulatory mechanisms.
Immunotherapy is a medical strategy that harnesses the immune system to treat diseases. Immunologists study how the immune system recognizes and responds to pathogens, abnormal cells, and foreign substances, which further help them develop suitable immunotherapies that enhance or modulate immune responses. Immunotherapies are targeted toward the creation of treatments for autoimmune disorders (type I diabetes, Graves disease, Addison disease, Rheumatoid arthritis, etc.), cancer (breast cancer, cervical cancer, liver cancer, prostate cancer, etc.), allergies, and more. By understanding the immune responses, immunotherapists formulate personalized therapies, vaccine development, and the production of monoclonal antibodies (antibodies that target specific disease-causing agents). They can also manipulate the immune system’s activity to enhance immune responses, suppress overactive reactions, reprogram cells, and combat various medical conditions.
Xenotransplantation is the process of transplanting organs or tissues from one species to another. Immunology plays a crucial role in xenotransplantation by driving the understanding of immune responses, rejection mechanisms, and ways to mitigate them. Its insights contribute to the development of safer and more effective strategies for transplanting organs or tissues across species. Xenotransplantation faces significant immunological challenges due to differences between the donor animal’s tissues and the recipient’s immune system. Immunologists study these differences to understand potential rejection and immune responses, such as hyperacute rejection in pig-to-human xenotransplantation, cell-mediated rejections, immunosuppression, immune-regulating proteins, inflammatory responses, immune tolerance, and risk of cross-species infections.
18. Developmental immunology
Developmental immunology investigates the formation, maturation, and function of the immune system throughout various life stages. It explores fetal immune development, neonatal immunity, changes during puberty and ageing, and the immune system’s role in brain development. It also analyzes how immune responses are influenced by hormonal shifts, the thymus, and microbiota. By understanding these processes, immunologists gain knowledge of immune-related vulnerabilities, autoimmune disorders, and infections at different life stages. Developmental immunology provides a comprehensive view of how the immune system evolves from birth through ageing, influencing health outcomes and disease susceptibility.
19. Animal models
Animal models play a significant role in immunology for understanding immune responses, diseases, and therapeutic interventions. Animal models are crucial in vaccine development and predicting human vaccine responses, and are ideal test subjects (allowing study of immune cell functions and interactions within a living system). Immunologists utilize these models to replicate human diseases, investigate immune mechanisms, and assess potential treatments.
20. Environmental immunology
Environmental immunology is a scientific field that studies how our immune system interacts with the environment. It explores how factors like pollution, allergens, and toxins can affect our body’s defences. Studying ecology emphasizes the relationships among living organisms and their environments in shaping immune responses and health outcomes. Environmental immunology or ecoimmunology helps us understand that the immune system is deeply intertwined with ecological factors (environmental changes, pollution, habitat disruption, etc.) which can impact the prevalence of diseases and alter the immune responses of organisms.
21. Comparative immunology
Comparative immunology investigates the immune systems of various species (plants, animals, and humans), aiming to understand the similarities and differences in how different organisms defend themselves against pathogens and diseases. By comparing the immune responses of diverse species, immunologists gain valuable insights into the fundamental principles of immunity. Comparative immunology also explores the variations across species that show how different organisms have adapted to their specific ecological niches. Due to this, some species may have more robust innate immunity, while others rely on adaptive immune responses. Moreover, comparative immunology helps in the development of treatments for various diseases by identifying common immune pathways that can be targeted for therapeutic purposes. It also aids in understanding zoonotic diseases (transferring from animals to humans), by examining the immune responses of reservoir host species.