MedSurg Ch 18 Assessment of Immune Function

Innate (natural) Immunity

provides the first and second lines of defense. The first line consists of physical, biochemical, and mechanical barriers that offer surface protection to prevent the invasion of microbes. When those barriers are breached, the second line of defense, the inflammatory response, is initiated to prevent and/or limit infection, clean out the debris of dead cells, and initiate tissue healing

Provides the first and second lines of defense

Innate (natural) Immunity

Inflammatory response

is initiated to prevent and/or limit infection, clean out the debris of dead cells, and initiate tissue healing. The first and second lines are nonspecific, responding the same way for any invasion

Second line of defense

Inflammatory response

Adaptive (acquired) immunity

occurs by natural exposure; infection, transfer of maternal antibodies, or artificial exposure; vaccination; or infusion of immune serum globulin. This type of immunity is specific and protects by way of cellular-mediated and humoral-mediated mechanisms

Primary lymphoid organs

include the thymus and bone marrow

Secondary lymphoid organs

include the spleen, lymph nodes, tonsils, adenoids, and Peyer’s patches. The cells and proteins include leukocytes (WBCs), T and B lymphocytes (T cells and B cells), cells involved in the inflammatory response, antibodies, signaling proteins (cytokines), and other protein systems (complement system) that support the immune response

Lymph Nodes and the Lymphatic System

Fluid continually filters out of the blood and into the interstitial space, the majority of which is reabsorbed back into the bloodstream. The lymphatic system is a network of vessels that transports excess interstitial fluid that has not been reabsorbed (lymph fluid) back to the bloodstream, helping to maintain fluid balance.

This system contains thousands of lymph nodes strategically located superficially and deep within the tissues near the lymphatic vessels. The nodes are small glandular structures that house macrophages, lymphocytes, and monocytes that actively filter and phagocytize microorganisms and other invading particles from circulating lymphatic fluid.

The lymph fluid moves through the lymphatic vessels, eventually emptying into the lymphatic ducts, the right lymphatic or thoracic duct, and returning to the general circulation through the subclavian veins. This filtering process prevents unwanted substances from reentering the bloodstream

Thymus

a soft organ located within the chest cavity near the heart. It starts off large in children and decreases in size into adulthood. It is the central lymphoid organ that produces thymosin (a hormone that stimulates T-cell production) and is where T-cell development takes place

Bone marrow

myeloid tissue, consisting of red (active) marrow and yellow (inactive) marrow. This is where B- and T-lymphocyte formation and differentiation of B cells and T cells occur. B cells stay within the bone marrow to mature. T cells migrate to the thymus to mature and become active as regulatory T cells (suppressor T cells) or effector T cells (helper T cells and cytotoxic T cells

Spleen

Approximately the size of a fist, the it is located in the left upper quadrant of the abdominal cavity. As a part of the lymphatic system, it serves as a blood filter. It is divided into compartments that contain red and white splenic pulp. The red pulp serves as the filtering site for old or damaged red blood cells. It can also store blood. The white pulp of lymphoid tissue houses lymphocytes and macrophages, filtering unwanted debris like a lymph node

Red pulp of the spleen

serves as the filtering site for old or damaged red blood cells. It can also store blood

White pulp of the spleen

pulp lymphoid tissue that houses lymphocytes and macrophages, filtering unwanted debris like a lymph node

If it is removed due to accident or disease, the patient may become immunocompromised, with high-risk patients requiring lifetime antibiotics

the spleen

Tonsils, Adenoids, and Peyer’s Patches

Additional lymphoid tissues that are located in close proximity to mucosal surfaces within the body and provide another means of protection against invading microorganisms

The tonsils

are located between the palatine arches on either side of the pharynx. They function as traps to protect against bacteria and viruses that are inhaled

Adenoids

Located at the nasopharyngeal border, they also defend against inhaled bacteria and viruses

Peyer’s Patches

lymphoid follicles located on the mucosa of the small intestine. They are known as intestinal immune sensors and defend against pathogens that gain entry to the intestinal tract

Leukocytes (WBC)

are formed in the bone marrow and lymph tissue; mature in the thymus or bone marrow; and are found in the blood, lymphatic system, spleen, and other body tissues. Are mobile units traveling through the bloodstream to defend the body against infection

Neutrophils, monocytes, eosinophils, basophils, and lymphocytes

leukocytes

Neutrophils

are phagocytes of early inflammation that destroy bacteria

Basophils

release heparin as an anticoagulant and histamine during the early inflammatory response

Eosinophils

are phagocytes that destroy allergens and combat parasitic infections

Macrophages

are phagocytes and initiators of the inflammatory response that digest and destroy, or phagocytize, microorganisms and other debris. They also activate helper T cells by secreting signaling proteins, called cytokines, and presenting processed antigens for destruction by the T cell

Lymphocytes

are active in both humoral immune responses and cell-mediated immune responses. They are formed in the bone marrow and are found in the lymph nodes, spleen, and thymus and enter the bloodstream through the lymphatic system

B lymphocytes (B cells)

are the cells involved in humoral immune responses. They are a subset of lymphocytes that mature in the bone marrow and produce antibodies, or immunoglobulins

Antibodies (or immunoglobulins)

bind with specific antigens, marking them for destruction by other components of the immune system, or directly neutralize the antigen by inhibiting an essential function necessary for its survival

T lymphocytes (T cells)

are participants in cellular-mediated immune responses. T-cell activation occurs when macrophages present the T cell with a phagocytized antigen.

Their main functions include the elimination of cells infected by pathogens, continued activation of the inflammatory response against persistent infections, and regulation of innate and adaptive immune responses

Immunoglobulins (antibodies)

B cells produce the following five classes: IgA, IgD, IgE, IgG, and IgM

IgA

is found in exocrine-gland secretions such as breast milk and tears

IgD

plays a role in B-cell activation

IgE

is associated with allergic reactions and parasitic infections

IgG

is effective against bacteria, viruses, and other toxins

IgM

the initial antibody produced after an infection

Cytotoxic T cells

respond to foreign cells, including tumors, non-self cells, and virus-laden cells

Helper T cells

are important cells in both adaptive and innate immunity. They augment the effectiveness of the innate immune response by activating macrophages. They augment both humoral and cellular immunity through the activation of B cells to produce antibodies. They also activate cytotoxic T cells and natural killer cells

Suppressor T cells

are activated by helper T cells when the immune response is no longer needed

Natural Killer (NK) cells

another form of T cell, targets virus-infected and tumor cells. As individuals age, the number of cells increases

Dendritic cells

are a type of macrophage that reside in lymphoid tissue and are the most potent of the antigen-presenting cells (APCs)

Antigen-presenting cells (APCs)

capture and engulf antigens, producing a molecule, the major histocompatibility complex (MHC), that identifies the antigen to aid in T-cell and B-cell recognition and response. When these cells attack an antigen, such as bacteria or a virus, they secrete signaling proteins (cytokines) that stimulate both the innate and adaptive immune response

Mast cells

are heavily granulated and are found in the skin and lining of the respiratory and gastrointestinal tracts. Similar to basophils, they release heparin and histamine during the early inflammatory response

Mast-cell degranulation is responsible for

many allergic reactions, including anaphylaxis, a severe systemic allergic reaction that is rapid in onset and can be fatal

Cytokines

which include interleukins (ILs), interferon (IFN), and tumor necrosis factor alpha (TNFα), are small proteins that act to regulate immune responses. They are produced in response to specific antigens by cells of the acquired immune system. They have systemic and local signaling effects that enable them to signal cells of the immune system

Interleukins (ILs)

occurs predominantly by macrophages and lymphocytes in response to the initiation of the inflammatory response. They are responsible for the general enhancement or suppression of inflammation and the stimulation of leukocyte production and maturation

Interferons

are proteins that protect against viral infections and tumor growth. They do not destroy a virus directly; rather, they prevent the virus from infecting the surrounding healthy cells and interfere with its ability to replicate

Tumor necrosis factor alpha

produced primarily by macrophages, enhances inflammation, and is involved in the regulation and production of immune cells

Interleukins and IFNs (interferons) rely on

TNFα to mount an effective inflammatory response

Compliment system

a complex system of proteins, provides cell-killing effects for both innate and acquired immunity. Initiation of the complement can activate every component of the inflammatory response as well as “complement” the antibacterial function of antibodies

Compliment proteins

are synthesized primarily in the liver and circulate in the bloodstream in an inactive form until activated by bacteria, viruses, fungi, tumor cells, antigen–antibody complexes, or endotoxins

Major histocompatibility complex (MHC)

To aid in the identification of self versus non-self, and to identify antigens to allow for a specific adaptive immune response, this group of proteins codes for the antigens on APC (antigen-presenting cells) cell surfaces to aid in recognition by the immune cells. That coding occurs when an APC cell, most commonly a dendritic cell, encounters an antigen, consumes it, and “presents” it on its surface to allow recognition by the immune cells

Anatomical defense

The epithelial cells of the skin, mucous membranes, and protective linings of the organs provide protection through the mechanisms of sloughing, coughing, sneezing, vomiting, and urination

Physical and mechanical barriers

biochemical surface and glandular secretions such as tears, saliva, perspiration, and earwax provide additional means of protection

The goal of inflammation

to prevent and/or limit infection and further damage to the involved area, remove debris, and prepare the area of injury for healing

Initiation of the inflammatory response

vasodilation and increased permeability of the capillaries stimulated by histamine released by mast cells, kinins, and other inflammatory mediators, such as prostaglandins and leukotrienes. Vasodilation increases blood flow to the inflamed area, facilitating leukocyte movement (chemotaxis) to the affected site

Cardinal signs of inflammation

redness and heat due to the increased blood flow and increased metabolic activity, edema due to the accumulation of fluid in the affected area, and pain due to the injury and swelling

All signs of inflammation

Redness and heat due to the increased blood flow and increased metabolic activity, edema due to the accumulation of fluid in the affected area, and pain due to the injury and swelling.

Drainage, serous exudate, or pus (a combination of dead immune cells and digested bacteria) may also be seen.

Systemically, fever, chills, malaise, and an elevated WBC count (leukocytosis)

For an immune response to be initiated

the foreign antigen must be recognized as non-self on presentation by APCs via the MHC molecule on its surface. Each T or B cell recognizes only one antigen, but together as a group, they can recognize a host of foreign antigens

When is the adaptive immune response acquired?

after birth and develops through active or passive immunity

In active immunity

antibodies or T cells are produced either after natural exposure to an antigen during illness or infection or after immunization

Passive immunity happens

when preformed antibodies or T lymphocytes are transferred from one individual to another.

For example, a newborn acquires immunity from their mother through the placenta, or an individual can acquire immunity through transfusion of antibody-laden blood products

Cellular-Mediated Response

a type of adaptive immune response that doesn't involve antibodies. Instead, it relies on the direct action of immune cells, primarily T lymphocytes (T cells), to recognize, target, and eliminate infected or abnormal cells.

This response is crucial for fighting intracellular pathogens, like viruses and some bacteria, as well as for controlling tumor growth and regulating inflammatory responses

Changes in the Aging Immune Response

The aged are noted to have a decline in T-cell function and antibody production when exposed to specific antigen challenges.

They also tend to have an increase in circulating antibody levels, leading to autoimmune disorders

Humoral-Mediated Response

After maturation in the bone marrow, B cells circulate through the lymphatic system as naive B cells with specific membrane-bound antibodies attached to their surface. When they encounter an antigen that “matches” their antibody, they become activated and divide into plasma and memory cells.

This process is commonly assisted by the helper T cell. Plasma cells are the effector cells, secreting antibodies to bind to the antigen. They have a short life span. Memory cells have the same membrane-bound antibody as the parent B cell. They remember and respond to the same antigen if there is repeated exposure. They have a longer life span

Agglutination

reaction between two antigens, causing them to clump. Facilitates phagocytosis and enables the body to clear itself of the invading organism

Opsonization

a process in which the antigen–antibody binding is coated with a pasty substance, also facilitates phagocytosis and assists in the clearing of the invading organism

Meds that have immune system side effects

Antibiotics, anti-inflammatory and immunosuppressive agents, antimetabolites, antineoplastic agents, and thyroid-suppressive therapy

The medical and surgical history is

important to obtain in addition to the family and social history because some immunological problems are genetic or chemically induced.

Also included should be nutritional status, infection history, prior immunizations, chronic illnesses, autoimmune disorders, and cancers

A fatty acid imbalance

can have suppressive effects

Illness leading to inadequate oral intake

may negatively alter nutritional status and the body’s ability to fight off infection and disease

Childhood and adult immunizations

should be assessed to make sure adequate protection is present

Nutritional status is

important to assess because suboptimal nutrition can negatively affect the immune system. Adequate vitamins and minerals are vital for the maturation of immune cells and their function

Tuberculin test administration and results and recent exposure to infections, sexually transmitted diseases

Are also important to assess

Physical assessment includes

the taking of vital signs; an inspection of the skin and mucous membranes; palpation of lymph nodes; and an examination of the neurological, respiratory, cardiovascular, gastrointestinal, genitourinary, and musculoskeletal systems.

In a patient with immune dysfunction, the normal inflammatory responses may be blunted, and subtle changes may be present

The nurse should perform a thorough assessment, inspecting __ for evidence of an immune disorder

each area of the patient’s body

Inspection assessment

Look for signs of hypothermia or hyperthermia, enlarged lymph nodes, or edema. Inspection of changes in skin color and skin integrity, rashes, dermatitis-type lesions, hematomas, petechiae, or purpura is equally important.

Changes in level of consciousness, cognition, gait, and vision and hearing are important to note.

Also important are changes in the respiratory system, such as tachypnea, air hunger, retractions, coughing, and nasal flaring.

Collect and examine the urine for sediment, odor, and blood. Stool samples should be assessed for blood, smell, and the presence of diarrhea

Listen to the lungs for adventitious (abnormal) breath sounds such as

crackles, wheezing, rubs, or rhonchi. Also note if there is any decrease in or absence of breath sounds.

Listen to heart sounds; note if tachycardia, rubs, or irregularity of heart rhythm is present.

Check for bowel sounds and note if they are hyperactive, hypoactive, or absent

Family history to assess

Malignancy

Anemia

Recent infections

TB history

Immune disorders

Hemophilia

Social history to assess

Lifestyle factors

Smoking status

Alcohol intake

Illicit drug use

Recent foreign travel

Employment history

Environmental exposure history

Splenectomy can cause

Loss of recognition and encapsulation of bacteria

Surgery can cause

Disruption of normal flora

Disruption of barrier defenses

Reduced neutrophil action

Trauma can cause

Disruption of barrier defenses

Contamination from soil, water, objects

Radiation therapy can cause

Decreased white blood cell production

Damage to first-line barrier defenses

Malnutrition can cause

Decrease in white blood cell count

Diminished neutrophil activity

Palpate the skin to

check the temperature and whether clamminess is present. Also examine the lymph nodes for evidence of enlargement or tenderness. With light palpation, move the skin over the areas where nodes may be palpable.

Nodes are not easily palpable in a healthy adult. If nodes are noted to be enlarged, tender, or fixed in position, this is cause for concern.

Explore the adjacent area and regions that are drained by the enlarged node for signs of infection or malignancy.

Cancerous nodes are not usually as tender as those from an infection or inflammatory process

To assess the abdomen

perform light and deep palpations with percussion to assess for hepatosplenomegaly (enlargement of the liver or spleen), palpable masses, and the presence of abdominal fluid or abdominal pain.

The liver and spleen may be enlarged because of infections, primary or metastatic cancer, or diseases of the blood or lymph system.

Joints should be examined for mobility, pain, swelling, warmth, and erythema

AIDS

caused by HIV, is an example of a secondary immune deficiency caused by a viral infection

Autoimmunity

refers to the body’s attack against tissue that is self, causing organ or tissue dysfunction

Hypersensitivity

occurs when an exaggerated response to an antigen is present

If the patient has a history of chronic bacterial infections

a complete blood count (CBC) with differential to evaluate individual leukocyte counts may be ordered

If the patient is fighting an infection

a CBC to evaluate the WBC count and inflammatory markers such as C-reactive protein may be drawn to evaluate responsiveness to a prescribed antibiotic

If neutropenia (low neutrophil count) with a low absolute neutrophil count (ANC) is present

reverse isolation may be necessary to protect the patient from infections

Neutropenia precautions

Immunosenescence

refers to changes to the immune system that occur with aging and their consequences—increased infection risk, increased risk of malignancy, and increased autoimmune disorders. Age is an essential factor to consider when assessing immunocompetence—immune competence may decrease as the immune system changes and weakens with age

Absolute neutrophil count (ANC)

calculates number of neutrophils available to fight bacterial infections

Absolute lymphocyte count (ALC

ALC calculates number of lymphocytes available to fight viral and opportunistic infections

Computed tomography scan (CT), magnetic resonance imaging (MRI), ultrasound, positron emission tomography (PET) scan

Imaging to detect presence of lymphadenopathy, tumor formation, or metastatic disease

PATIENT TEACHING - Computed tomography scan (CT), magnetic resonance imaging (MRI), ultrasound, positron emission tomography (PET) scan

If contrast necessary, confirm absence of iodine allergy or previous contrast intolerance.

Patient may be NPO for a period of time before the scheduled test.

If the patient is claustrophobic, sedation may be necessary.

For PET scan, blood sugar must be under 200 mg/dL.

For a PET scan

blood sugar must be under 200 mg/dL

Tissue allergy panel

tests for hypersensitivity. Tissue allergy panel

Tissue allergy panel education

Educate the patient about possible discomfort at injection site and positive wheal reaction

Erythrocyte sedimentation rate

C-reactive protein

Inflammation studies