Introduction to Immunity

Introduction to Immunity

• Immunity is the body's ability to resist infection and disease.

Innate Immunity

• Natural immunity is non-specific and responds the same way for any invasion.
• The first line of defense includes physical, biochemical, and mechanical barriers that offer surface protection to prevent microbe invasion.
• The second line of defense involves the inflammatory response to prevent/limit infection, clean out dead cell debris, and initiate tissue healing.

Acquired Immunity

• Adaptive immunity is the third line of defense.
• It occurs by natural or artificial exposure, such as infection, transfer of maternal antibodies/breastfeeding, or vaccinations.

Key Terms

• Immunocompetence is when the immune system identifies foreign microbes and inactivates them.
• Immuno-incompetence is when the immune system cannot mount a response to an antigen.
• Failure to initiate an immune response can lead to allergies, infection, cancer, or immunodeficiency disorders.
• Factors impacting immunity include age, medications, nutrition, genetics, physical/emotional stress, and illness.

Review of Anatomy

• Lymph nodes and the lymphatic system filter fluid out of blood and into interstitial space to maintain fluid balance.
• The thymus is a soft organ in the chest cavity where T-cell development occurs.
• Bone marrow is where B and T lymphocyte formation and differentiation occur.
• The spleen filters blood. Its removal can lead to a compromised immune system.
• Tonsils, adenoids, and Peyer's patches act as traps to protect against viruses and inhaled bacteria.

Cells of the Immune System

• Leukocytes (white blood cells) are mobile units that travel through the bloodstream to defend against infection.
• Neutrophils initiate immune response/inflammation.
• Monocytes found in circulation are innate/adaptive.
• Eosinophils are associated with allergic reactions.
• Basophils release histamine.
• Lymphocytes (B and T cells) coordinate adaptive immune responses.

B-Lymphocytes

• These lymphocytes mature in the bone marrow and produce antibodies or immunoglobulin.
• Upon first exposure to an antigen, B-lymphocytes proliferate into plasma cells, which secrete antibodies, and memory cells, which help mount a specific antibody response if the same antigen restimulates them.

T-Lymphocytes

• T-lymphocytes functions include the elimination of cells infected by pathogens, continued activation of inflammatory response, and the regulation of innate and adaptive immune responses.
• Types of T-Lymphocytes include cytotoxic T cells, suppressor T cells, and helper T cells.
• Natural killer (NK) cells are another form of T cell that targets virus-infected and tumor cells, increasing in number with age.

Immunoglobulins

• IgA is present in exocrine glands like tears, breast milk, sweat, and saliva.
• IgD activates B-cells
• IgE is associated with allergic reactions
• IgG protects against bacteria, viruses, and other toxins
• IgM is the first antibody produced in a primary response.

Dendritic and Mast Cells

• Dendritic cells reside in lymphoid tissue and are the most potent antigen presenting cells (APC).
• Antigen presenting cells capture and engulf antigens. They secrete signaling proteins stimulate the innate and adaptive immune response when attacking bacteria or viruses.
• Mast cells found in skin and the lining of respiratory and GI tracts.
• Mast cells release heparin and histamine during inflammatory responses and are responsible for many allergic reactions, including anaphylaxis.

Inflammatory Response

• The inflammatory response occurs due to tissue damage or exposure to hazardous compounds.
• The body initiates an inflammatory response to prevent/limit infection, remove debris, and prepare the area for healing.
• The initiation of inflammatory response involves vasodilation, increased permeability of capillaries, histamine release by mast cells, increased blood flow, and the engulfment of invading organisms.
• Erythrocyte sedimentation rate (ESR) indicates increased inflammatory activity.
• Cardinal signs of inflammation include fever, malaise, and chills.

Nursing & Physical Assessments

• Key aspects of nursing assessment/patient history include age, current medications, allergies, medical & surgical history, family/social history, nutrition, infection history, prior immunizations, and chronic illness.
• Physical assessment should consider constitutional symptoms, dizziness, changes in mental status, shortness of breath, chest pain, loss of appetite, bleeding, enlarged nodes, joint pain, and extremity swelling.

Diagnostic/Laboratory Studies

• Blood tests include complete blood count (CBC), chemistry panels, HIV test, and urinalysis.
• Skin tests include cultures and biopsies.
• Bone marrow biopsies include biopsy aspiration.
• Imaging includes chest x-ray, MRI, and CT scans.
• ESR and/or C-reactive protein levels are also measured.

Age Related Changes

• Immunosenescence can cause decreased immunological function, leading to less efficient immune responses.
• There is an increased production of autoantibodies and a decline in immune response, which results in malignant cells not being destroyed as quickly.
• Age related changes can lead to increased infections, autoimmune disorders, and increase cancer.
• Safety considerations for older adults include malnutrition, immunosuppression, medications, and socioeconomic factors.
• Elderly adults experiencing immunosenescence may experience increased risks for infection, malignancy and autoimmune disorders. They also may be on medications that impacts the immune system,

Vaccinations for Older Adults

• Recommended vaccinations for older adults include Pneumovax for adults over 65 at high risk.
• Adults may also need Shingrix or Zostavax for shingles as well as a high-dose flu vaccine containing 4x the antigen compared to a standard dose.

Primary Immune Dysfunction

• This occurs in people born with a deficient immune system that has limited ability to function.
• These are majority diagnosed in childhood, but can take years to present.
• In some instances, B-lymphocyte Deficiency can occur. This is usually XLA X Linked and seen primarily in males.
• T-lymphocyte Deficiency can also occur, e.g. DiGeorge Syndrome Autosomal dominant, 22 second chromosome

Primary Immunodeficiency Warning Signs

• Eight or more new infections within 1 year
• Two or more serious sinus infections within 1 year
• Two or more months on antibiotics with little or no effect
• Two or more pneumonias within 1 year
• Failure of an infant to gain weight or grow normally
• Recurrent deep skin or organ abscesses
• Persistent thrush in the mouth or elsewhere on skin after age 1
• Need for IV antibiotics to clear infections
• Two or more deep-seated infections
• A family history of immune deficiency

Secondary Immune Dysfunction

• Secondary immune dysfunction occurs after birth when damage to the immune system results from an extrinsic or external factor.
• It can be triggered by HIV disease, chemotherapy, malnutrition, or burns.
• Most immune deficiencies seen in the adult clinical setting are secondary.

Immunosuppressive Therapy Options

• IV Immune globulin (IVIG) provides short term passive immunity and attempts to normalize a compromised immune system.
• Low dose prophylactic broad-spectrum antibiotics prevent infection, even without patient-experienced symptoms. The antibiotic course can be twice as long as a healthy adult.

Nursing Assessment of Suppressed Immune Systems

• Ask yourself what symptoms a patient with a suppressed immune system may present with?
• Vital signs include hypotension and tachycardia.
• Lung sounds may indicate a respiratory infection.
• Skin symptoms may be rashes or lesions.
• Lab results can include WBC count and results from ESR or C-Reactive Protein tests.

Priority Nursing Interventions

• Prevent exposure through handwashing and protective isolation with limited visitors.
• Administer medications, like IV or PO immune globulin and prophylactic antibiotic therapy
• Provide patient education, including safe food handling, drinking water, domestic animals, unsanitary conditions, signs and symptoms of infection, good handwashing, and how to avoid contact with sick individuals.

Excessive Immune Responses

• Autoimmunity is when the body initiates an immune response against itself.
• Antibodies are formed that respond to normal, healthy cells and tissue because the body fails to recognize cells as itself.
• Examples of autoimmune diseases include Lupus, RA, Graves disease, Myasthenia Gravis, and hematological disorders.

Hypersensitivity Reactions Types

• Type I: Immediate, rapid allergic reaction.
• Type II: Cytotoxic reactions include the wrong blood transfusion and thrombocytopenia.
• Type III: Immune complex reactions include lupus and Rheumatoid arthritis.
• Type IV: Delayed hypersensitivity includes contact dermatitis to poison ivy
• Type V: Stimulated reactions include Graves Disease.

Type 1 Reactions

• The determination if it is local or systemic can be evaluated by assessments.
• Most common is allergic rhinitis (a local reaction)
• Causes are typically dust, mold and animal dander
• Common clinical manifestations are nasal discharge, sneezing, inflammation of the nasal passages, itchy, watery eyes, headache, sinus pressure.
• Treatment is avoidance of the triggers, can also be treated with Antihistamines (Diphenhydramine, Cetirizine, Loratadine, Fexofenadine (Allegra). Steroids can also treat, reduce inflammatory response.

Type 1 Reactions cont.

• Most severe form is anaphylaxis.
• Caused by food, certain medicine and insect bites.
• Manifestations include Dyspnea, shortness of breath, audible wheezes/crackles, skin reaction, nausea/vomiting/diarrhea, anxiety, flushed/warm, swelling.
• Requires vasodilation occurs that causes Hypotension, rapid weak pulse, dilated pupils, and possible passing out.

Managing Anaphylaxis

• Remember to prioritize the ABCS!
• Speed
• Recognize signs and symptoms
• Maintain airway
• Prevent spread of allergen
• Administer medications to minimize and contain response
• Prevent and treat shock

Type IV Reactions

• A person may have local contact dermatitis before it progresses and becomes systematic.
• Clinical Manifestations are raised areas of skin, edematous, fluid, reddened skin and itchy skin.
• Management is prevention, antihistamines, and steroids. In severe cases, can use oxygen, epinephrine, and steroids.

Medication Management for Allergic Reactions

• Diphenhydramine (histamine blocker) can treat edema and pruritus.
• Albuterol (Bronchodilator) relaxes the lungs to make breathing easier.
• Epinephrine (stimulates alpha and beta receptors). Alpha causes vasoconstriction whereas beta receptors relax bronchial smooth muscle. Used mostly for severe reaction.

Avoiding Triggers

• Ways to prevent exposure to allergen
• Signs to look out
• Know how to react in a timely manner if exposed

Latex Allergies

• Healthcare workers, patients who have undergone multiple surgical procedures, females, and patients with spina bifida are at high risk for latex allergy.
• An alert can also relate to foods such as avocado, chestnut, mango, papaya, passion fruit, tomato, raw potato, peach, banana, and kiwi.
• Nursing should administer ordered medications, utilize BP cuff, avoid touching skin, and avoid injecting through rubber ports.

Nursing Diagnoses and Considerations

• Considerations include infection risk, tissue damage, and impaired oxygenation.
• A patient may also have deficient knowledge, and one should always prioritize the ABC's.