Learning Objectives
By the end of this section, you will be able to:
- Discuss the normal anatomical and physiological findings of an immune response
- Identify key components to incorporate into an immune system–focused assessment
- Discuss the effects and role of immunosuppressive medication in patient care
- Discuss recent advances in immunology
The body’s specific, protective response to a foreign agent or organism is known as immunity. Through a variety of responses, both antibody mediated and cell mediated, the healthy immune system eliminates foreign substances or invaders it deems to be “nonself.” Patients who are immunocompetent have an efficient immune system that is able to carry out functions properly. Patients who are immunocompromised do not have a properly working immune system; as a result, they are at risk for hypersensitivities, autoimmune disorders, infections, and immunodeficiencies.
Anatomy and Physiology Overview
The immune system is an intricate and complex system of specialized physiological structures that work in tandem to protect the body. The immune system’s main tasks include the following (Institute for Quality and Efficiency in Health Care, 2020a):
- recognizing and neutralizing harmful substances from the environment
- recognizing and destroying malignant cells
- fighting and removing from the body disease-causing pathogens, such as bacteria, fungi, viruses, and parasites
- removing and destroying dead or damaged cells
Although it is always at work, a properly functioning immune system carries out its tasks automatically and without a person’s conscious awareness. As long as they feel well, a person likely will not think about how hard their immune system is working. A weakened immune system is noticeable, however; a person will become ill after being exposed to an agent that the body cannot adequately defend against and develop symptoms that draw their attention to their state of ill health.
To effectively care for patients with a weakened or improperly functioning immune system, the nurse must understand the system’s anatomy and physiology. The nurse also needs a solid educational foundation in these topics to educate patients and their families, thereby promoting optimal health and preventing disease.
Anatomy of the Immune System
The immune system is made up of many cells, tissues, and organs (Figure 29.2). White blood cells, or leukocytes, are the primary cells involved in an immune response. These cells are produced in the bone marrow and move through the body in a colorless fluid called lymph, which also contains water, fats, proteins, electrolytes, and antibodies.
Leukocytes can be divided into different types (Figure 29.3), including granulocytes (neutrophils, eosinophils, and basophils), monocytes, and lymphocytes (T cells, B cells, and natural killer cells). Granulocytes are white blood cells that are involved in defending against infections (Tigner 2022). The different types of granulocytes are the following:
- Neutrophils are the most common type. They quickly respond to infections and destroy bacteria and fungi.
- Eosinophils help fight off parasites and are involved in allergic reactions.
- Basophils are the least common type. They release chemicals like histamine during allergic reactions to help the immune response.
Monocytes are cells that become macrophages when they move into tissues. They eat and digest bacteria, dead cells, and other debris. Lymphocytes are crucial for the body’s immune response. The three types of lymphocytes are the following:
- T cells help other immune cells and kill infected or cancerous cells.
- B cells make antibodies that target and neutralize invaders like bacteria and viruses.
- Natural killer (NK) cells destroy infected or cancerous cells without needing to recognize a specific antigen.
Lymphoid tissues include the spleen and lymph nodes (Figure 29.4). The red pulp of the spleen is where injured and old red blood cells are destroyed and the iron recycled back into the body. The white pulp of the spleen houses a concentration of lymphocytes. The lymph nodes keep foreign material from entering the bloodstream by removing it from the lymph system via channels and capillaries. The lymph nodes also serve as a center for proliferation of immune cells.
Other lymphoid tissues and organs include the appendix, thymus, intestines (specifically the Peyer patches), tonsils, adenoids, and bronchus-associated lymph tissues. These organs house immune cells that defend the body’s mucosal surfaces against pathogens and microorganisms (Rawer, 2021).
Function of the Immune System
The overall function of the immune system is to recognize and destroy foreign antigens. The body’s natural immunity (also called innate or nonspecific) is present at birth, and its acquired immunity (also called adaptive or specific) develops after birth (Table 29.1). Each type plays a distinct role in defending the body, but the respective components are co-dependent.
| Characteristic | Natural (Innate) Immunity | Acquired (Adaptive) Immunity |
|---|---|---|
| Type | Inherited | Acquired during life (exposure, vaccination) |
| Duration | Life | Varies |
| Specific | No (broad) | Yes |
| Mechanisms | Innate immune cells, barriers/defenses (physical, chemical) | Antibodies (T, B cells) |
| Vaccination | No | Yes |
| Timing | Immediate response | Gradual response |
| Memory | No | Yes |
Natural Immunity
Natural immunity is the first line of a host’s defense. The innate immune system reacts quickly when contact is made with pathogens. White blood cells are key to an effective response. The macrophages work to digest and dissolve pathogens. Monocytes play a role in phagocytosis, engulfing and destroying foreign bodies. Eosinophils protect against parasites; they also increase in number in response to allergic reactions and stress. Basophils release chemotactic substances, such as serotonin, histamine, and heparin, in allergic reactions. Where inflammation occurs, the neutrophils are the first cells to arrive. The natural killer cells destroy tumor, fungi, and viral-infected cells as well as foreign tissues.
Other substances also play roles in the innate immune response, including several proteins: interferons signal the substances involved in defense against viruses, and interleukins are sent messages to direct the actions of the immune system cells, including modulating inflammation. Mucous membranes throughout the body produce secretions that bind invaders until they can be destroyed or removed. Hairlike structures called cilia (singular: cilium) remove invaders found in the respiratory tract. The cough reflex is also part of the natural immune response, as the body attempts to remove antigens from the respiratory or digestive system and inhibit them from invading the body further.
The stomach and intestines also play roles in the innate immune response. The stomach produces hydrochloric acid and enzymes that break down proteins and decompose foreign pathogens. The intestinal flora also fend off infections as antibody-producing cells live in the intestinal mucosa (Rawer, 2021).
Acquired Immunity
Acquired immunity is adaptive and complex. It responds to a specific threat, or antigen, by producing antibodies that are designed to target that antigen. It must be able to remember all the various antigens that it encounters to efficiently respond when particular antigens make recurrent attacks.
Lymphocytes play key roles in the adaptive immune system. This is how they break down. B cells, which mature in the bone marrow, form antibodies (also called immunoglobulins) that target specific antigens. T cells, also known as T lymphocytes, mature in the thymus, function to control viral infections, destroy cancer cells, and are also involved in hypersensitivity reactions. T lymphocytes also migrate through the host to monitor body cell surfaces for changes. When T cells make contact with a recognition mark or antigen, they activate to stimulate B-lymphocyte division. T killer cells then terminate infected or degenerated cells. T-helper cells support the immune response. The T-suppressor cells dismiss the immune response and also reduce the risk of autoimmune diseases or allergic reactions by suppressing the immune response in certain interactions (Rawer, 2021).
Clinical Safety and Procedures (QSEN)
QSEN Competency: Safety. Infection Prevention
Disclaimer: Always follow the agency’s policy for infection prevention.
Definition: Minimizes risk of harm to patients and providers through both system effectiveness and individual performance.
Knowledge: The nurse will analyze basic safety principles, understand evidence-based practice infection prevention standards, and reflect on unsafe nursing practices.
Skills: Demonstrate effective infection prevention strategies to reduce the risk of harm when providing care to patients. This may include but is not limited to practicing frequent, proper handwashing, using personal protective equipment (PPE), using aseptic technique, following disinfection procedures, practicing safe injection, providing patient education, participating in surveillance, and staying current on evolving standards and practices that help prevent infection in the health-care and community settings.
Attitudes: The nurse will respect their individual role in preventing infection by adhering to safe, evidence-based practice standards.
(QSEN Institute, n.d.)
Assessment of the Immune System
Assessment of the immune system starts with obtaining the health history of the patient and performing a physical examination. The nurse should determine the patient’s nutritional status and history of immunizations, infections, allergies, surgeries, medications, blood transfusions, and disease and disorder states, such as cancer, chronic illnesses, or autoimmune conditions. The nurse should also palpate the lymph nodes to assess for signs of inflammation or illness, including tenderness, enlargement, and movability. For example, firm, painless lymph nodes can be a sign of cancer, while inflamed lymph nodes from an infection can be tender and movable.
Additionally, the nurse will assess the skin and mucous membranes as well as the neurosensory, cardiovascular, genitourinary, musculoskeletal, gastrointestinal, and respiratory systems, for specific and nonspecific signs of illness, injury, and inflammation, such as redness, fever, and swelling.
Health History
The health history of a patient is an important indicator of how well the immune system functions. Older adults are at a greater risk for immunosenescence, the gradual deterioration of the immune system due to natural aging processes (Borgoni et al., 2021). Changes due to aging contribute to a variety of problems and put older adults at an increased risk for infections, metabolic diseases, autoimmune diseases, neurological disorders, and osteoporosis. The aging immune system’s inability to recognize malignant cells may also be a contributing factor of cancer in older people (Borgoni et al., 2021).
Gender is another important component. There are differences in immune system functions between males and females. Sex hormones contribute to the development and activity of the immune system. Both innate and adaptive immune systems have receptors for sex hormones and respond to hormonal cues (Moulton, 2018). Consequently, differences in sex hormones help to explain the greater prevalence of autoimmune diseases in females than in males (Pennell et al., 2012)
A person’s nutritional status likewise is vital to the efficiency of their immune status. Nutritional deficiencies in micronutrients have been linked to a decline in immune function. Specifically, deficiencies in zinc are associated with several diseases, because zinc plays an important role in immune function, homeostasis, and apoptosis, which is the normal and controlled death of cells. An inadequate intake of protein can result in the atrophy of lymphoid tissue, decreased production of T cells, impaired phagocytic function, and a reduced antibody response—all factors that can make a person more susceptible to infection (Venter et al., 2020).
The nurse should also ask the patient about their immunization history throughout their lifespan. This includes vaccinations, such as influenza, COVID-19, pertussis, herpes simplex, and pneumococcal disease, as well as childhood and adolescent immunizations, such as measles, mumps, rubella, hepatitis A and B, DTaP, human papillomavirus (HPV), polio, rotavirus, and meningococcal. This history allows the nurse both to assess the patient’s immunity against diseases and to determine if a patient needs an immunization. It also provides the nurse with an opportunity to educate the patient about the need for vaccines.
Link to Learning
The Centers for Disease Control and Prevention (CDC) provides free resources outlining vaccine schedules for children and adolescents from birth to 18 years old as well as adults 19 years of age and older.
Another important component of the patient’s health history is the patient’s known past or present exposure to various infections that can contribute to immunodeficiency, including lifestyle risk factors. The nurse will want to assess the patient’s exposure to tuberculosis; blood-borne pathogens, such as hepatitis B, C, D, or HIV; and sexually transmitted infections, such as gonorrhea, syphilis, HPV, and chlamydia. Assess lifestyle risk factors as well, including sexual partner history and drug use. Finally, the nurse should assess for recurrent infections, fevers of unknown origins, lesions, and any type of drainage from a lesion or wound, noting known or suspected dates of exposure, test results, and types of and responses to treatment.
The nurse should ask the patient about allergies. Allergies may include dust, pet dander, cosmetics, pollens, plants, medications, latex, vaccines, or food. The nurse should assess the symptoms experienced, their severity, and the presence or absence of any seasonal variation. The history includes asking about allergy testing, treatments, and effectiveness of treatments. It is crucial that the nurse document all patient allergies and, for those reporting food or medication allergies, create identification bands and alerts to notify other members of the health care team.
History: Disorders and Diseases
Autoimmune disorders result when the immune system malfunctions and attacks the body’s own healthy cells, tissues, or organs. Instead of attacking a nonself tissue or invader, the body attacks itself (Figure 29.5). Autoimmune disorders can affect any part of the body and weaken bodily function. Examples include diabetes, lupus, rheumatoid arthritis, and multiple sclerosis (U.S. Department of Health and Human Services, 2022). It is important that the nurse assess for autoimmune conditions to determine how well the patient’s immune system functions and if the patient is at risk for infections. The nurse should obtain information about the onset, severity, remissions, and exacerbations of each documented disorder, along with any functional limitations and the types and effectiveness of current or past treatments. The nurse should also obtain information about any family history of autoimmune conditions, because there can be a genetic predisposition.
Neoplastic diseases are conditions that cause a neoplasm, or tumor—an abnormal growth of cells in a confined area, which may be benign or malignant. A benign tumor is noncancerous and unable to spread to other tissues or organs. A malignant tumor is cancerous and can spread to other tissues or organs in the body, a process known as metastasis. The nurse should obtain the patient and family history of cancer, including type, onset, test results, past and current treatments received, alternative therapies used, and response to treatments; family histories should also include the maternal or paternal relationship of the affected family member to the patient. Immunosuppression can contribute to the development of cancer, and cancer treatment can further contribute to immunosuppression. For example, chemotherapy can diminish bone marrow function and destroy the important lymphocytes needed for adequate immune responses (Cancer Research UK, 2021).
History: Psychoneuroimmunology Factors
The study of how the immune system and central nervous system interact is called psychoneuroimmunology. Neurotransmitters, hormones, and neuropeptides have been found to regulate immune cells; in turn, immune cells are capable of communicating with nervous tissue through the secretion of a wide variety of cytokines. The hypothalamus can communicate a warning to the body when it recognizes a potential predator. The hypothalamus can also recognize the release of prostaglandins, interleukins, interferons, histamine, and serotonin during the inflammatory response.
Determining the psychological status of the patient is an important component of the health history. Stress can negatively affect the effectiveness of the immune system and contribute to illness or infection. This is due to the elevated levels of cortisol-releasing hormone, adrenocorticotropic hormone, and cortisol, which can affect the immune system cells in both the short and long term by suppressing the immune response and, over time, reducing its effectiveness (Tausk et al., 2008). Behavioral strategies, including meditation, relaxation, biofeedback, imagery techniques, and hypnosis, can improve a patient’s immune response; the nurse should assess the patient’s response to and use of these strategies, as applicable.
History: Medications and Blood Transfusion History
Part of obtaining a health history includes asking the patient for a list of current and past medications. Medications, such as antibiotics, nonsteroidal anti-inflammatory drugs, corticosteroids, cytotoxic agents, and anesthetic agents can suppress the immune system. The nurse should also ask about the use of over-the-counter medications and herbal supplements. While there has not been rigorous testing of all herbal supplements and over-the-counter medications, some are known to cause immunosuppression. It is best practice to obtain information about the patient’s usage and educate them about problematic effects that may alter their immune response. For example, red yeast rice may be used to lower high-density lipoprotein and low-density lipoprotein. This herb has been found to work as an immunosuppressant, however.
The patient’s blood transfusion history is also important, because previous exposure to foreign antigens through a transfusion can be linked to an improperly functioning immune system. Although blood to be transfused is tested for HIV prior to being administered and the risk of HIV from a blood transfusion is extremely low, a small risk is still possible.
History: Lifestyle Considerations
A person’s lifestyle can greatly affect how well their immune system functions. Factors, such as smoking, poor nutritional status, alcohol consumption, sexually transmitted infections, illicit drug use, stress, lack of sleep, and environmental exposure to radiation and pollutants have been linked to an impaired immune system. Conversely, someone who overexercises is also at risk for a poor functioning immune system due to the physiological stress on their body. The nurse must ask questions to determine any lifestyle factors that may affect the patient’s immune system.
Following are examples of questions the nurse may ask to elicit this key information from a patient:
- Do you smoke? How much and for how long?
- What do you normally eat and drink?
- Do you drink alcohol? How much and for how long?
- Do you use any substances? Which ones and for how long?
- Are you feeling stressed out? How would you rate your stress from low to high? What do you to do manage your stress?
- How do you sleep? What time do you go to bed and wake up? Do you feel rested?
- Do you get physical activity during the day? Do you have a workout routine? Are you sitting for most of the day without a break to stand up and move around?
- Are you sexually active? What steps do you take to protect yourself from sexually transmitted infections? Have you ever been diagnosed with a sexually transmitted infection, had symptoms of one, or had a partner who had one?
- Are you concerned about exposure to chemicals at your job or at home? Have you had tests like medical scans that used radiation? Are you concerned about the air quality or levels of pollution in your community?
- Have you been sick recently? Has anyone in your home had a contagious illness recently?
- Do you take any medications or use supplements, including over-the-counter vitamins, medicines, or alternative medicine therapies?
The nurse should also educate the patient and family on the importance of modifying lifestyle factors to promote optimal health (Harvard Health Publishing, 2021).
Clinical Judgment Measurement Model
Analyze Cues: Asking Subjective Questions
Before analyzing cues, the nurse must make sure they have enough data to interpret the information. For example, if a patient reports a sore throat, the nurse must recognize the sore throat as a cue to ask follow-up questions such as these: “When did it start?” “How severe is the pain?” “Is there anything that makes it worse or better?” “What other symptoms are you having?” “Have you been exposed to anyone with an illness that you are aware of?” The patient’s response will allow the nurse to begin critically thinking about the information in order to hypothesize the likely cause and appropriate treatment. By asking subjective questions, the nurse is able to determine what actions to take next.
Physical Assessment
A physical examination to assess a patient’s immune system includes palpation of the lymph nodes found in the anterior and posterior cervical areas, as well as the supraclavicular, axillary, and inguinal lymph nodes. The nurse will determine whether any nodes are swollen or tender. The nurse will also check the skin and mucous membranes for any lesions, purpura, urticaria, dermatitis, inflammation, or discharge. Take the patient’s temperature and assess their joints for tenderness, edema, warmth, or limited range of motion. The nurse should also assess the patient’s neurosensory, cardiovascular, genitourinary, musculoskeletal, gastrointestinal, and respiratory systems for signs of possible immune dysfunction, including fever, weakness, fatigue, weight loss, and pain. The nurse must document all findings.
Diagnostic Evaluation
Diagnostic evaluation of the immune system includes various blood and skin tests (Table 29.2). These tests may include humoral, or antibody-mediated, immunity tests, or cellular, or cell-mediated, immunity tests.
| Category | Test | What It Checks For |
|---|---|---|
| Humoral immunity (antibody mediated) | B-cell quantification with monoclonal antibodies | Number of B cells, overall immune system functioning, and signs of deficiency |
| Specific antibody response | Antibodies for specific antigens, signs of specific infections, assess response to vaccines | |
| Total serum globulins | Number of globulins, health of immune system, signs of deficiency | |
| Individual immunoglobulins (IgG, IgA, IgM) | Levels of specific antibodies, health of immune system, response to vaccines | |
| Cellular immunity (cell mediated) | Total lymphocyte count | Number of immune cells, health of immune system, signs of deficiencies |
| Cytokine production | Number of cytokines being produced, signs of inflammation, infection, autoimmune disease | |
| Helper and suppressor T-cell functions | T cells’ ability to control immune response, health of immune system, and signs of deficiency | |
| T-cell quantification with monoclonal antibody | Number of specific T cells | |
| Delayed hypersensitivity skin test | T-cell function by reaction to a harmless substance, assess vaccine response or look for immunodeficiencies | |
| Lymphocyte response to antigens, mitogens, and allogenic cells | Immune cell reaction to different triggers, assess immune system health, signs of deficiencies | |
| Other tests | Bone marrow biopsy | Immune cells in bone marrow, diagnose diseases of bone marrow or causes of poor immune response |
Collaborative Management with Immunosuppressive Therapy
Collaborative management of a patient with immunodeficiency will vary depending on the diagnosis and severity. The interdisciplinary team may include nurses, psychologists, primary care physicians, infectious disease doctors, rheumatologists, oncologists, endocrinologists, social work, physical therapists, dietitians, or occupational therapists. Treatments may vary to include medications, infusions, surgery, chemotherapy, radiation, lifestyle modifications, counseling, or rehabilitation.
The interdisciplinary team is involved in the diagnosis and management of immune function disorders, and all members must be aware of the physical discomfort and psychological reactions that may be associated with testing and treatments. Patients may experience grief or anxiety associated with test results or possible implications of a diagnosis that may affect their personal relationships, employment, and future health. The nurse should counsel, educate, and be supportive throughout the process as well as provide resources on counseling and education when needed.
Medical management may include immunosuppressive therapy. This therapy may be prescribed for autoimmune diseases or for those undergoing organ or stem cell transplantation. Immunosuppressive therapy is designed to stop the immune system from mistakenly attacking healthy cells and tissues. Prior to organ or stem cell transplants, immunosuppressive agents are prescribed to prevent the body from rejecting or attacking the transplanted material. Potential side effects of these agents may include hyperglycemia, fatigue, hair loss, headaches, high blood pressure, osteoporosis, tremors, weight gain, nausea, and/or vomiting. The nurse or prescriber must educate the patient to take their medications as prescribed, despite any side effects, as skipping a dose can result in a flare-up or worsening of the condition the drug is intended to treat. It could even cause the patient’s body to reject the transplanted organ or cells.
Taking immunosuppressants can have more serious, even life-threatening, consequences, as suppressing the immune system puts the patient at increased risk of infection from any number of pathogens. The patient should be educated on signs and symptoms of infection and the need to immediately report symptoms, such as a fever of 100.5°F (38°C) or greater, decreased urine output, bloody urine, flu-like symptoms, tenderness around the transplanted organ, and skin changes such as rashes or lesions with drainage or redness (Cleveland Clinic, 2023).
Advances in Immunology
Chapter 31 Cancer explores in detail advances in immunology such as stem cells and immunotherapy for cancer, but it is worth briefly discussing each topic in the context of immunological function.
The stem cells are cells in the earliest stage of development, before they have become specialized—that is, before they have become blood cells, liver cells, muscle cells, and so on. Stem cells can be multipotent (can become the cell type they came from) or pluripotent (can become any other kind of cell). Consequently, they can develop into many different cell types in the body during early life and growth. They also continually replenish the body’s supply of red and white blood cells. When a stem cell divides, the resulting two daughter cells may both be stem cells; they may also both be differentiated, or specialized. Alternatively, the division may result in one stem cell and one differentiated cell (U.S. Department of Health and Human Services, 2021). Table 29.3 lists the main categories of stem cells (U.S. Department of Health and Human Services, 2021).
| Embryonic Stem Cells | Nonembryonic (“Adult”) Stem Cells | |
|---|---|---|
| Multipotent | Induced Pluripotent | |
| They are found in embryos. | They are found in fully developed tissues and organs. | They are adult stem cells that have been transformed in a laboratory to become pluripotent (or nearly so). |
| They are pluripotent, which means they can become any of the cell types in the adult human body. | They can become only the type of cell that makes up the tissue or organ where they came from. | They appear to be identical to embryonic cells and can turn into multiple cell types, but so far scientists have not been able to make them fully pluripotent. |
Studies have shown stem cell transplantation to have therapeutic effects. In some cases, it has even restored destroyed immune systems (Ebrahimi et al., 2021). Research is ongoing, however, and concerns remain regarding the efficacy and safety of the therapy.
The emerging field of genetic engineering is designed to enable the replacement of defective or missing genes using recombinant deoxyribonucleic acid (DNA) technology. There are two facets of this technology relevant to immunotherapy. In one, scientists combine genes from two different types of organisms to produce proteins, lymphokines, and monokines, which have the ability to improve the functioning of the immune system. In the other, scientists attempt to restore normal gene function when a particular gene is missing or defective. This generally involves inserting a recombinant gene into a harmless virus; when the virus joins with a cell in the immune system, it inserts the missing gene into the cell’s DNA, fixing the anomaly (Lanigan et al., 2020).
Remember that one function of the immune system is to find and attack malignant cells. Some cancer cells may go undetected by the body due to genetic changes that make them less noticeable, proteins on the cell surface that turn off immune cells, or changes to the normal cells around the cancer that alter how the immune system responds. Immunotherapy treatments are designed to boost a person’s own immune system to better recognize and destroy cancer cells. This knowledge has led to more and better treatment options, such as vaccines, monoclonal antibodies, immune checkpoint inhibitors, and cytokines (National Cancer Institute, 2019).