Immune Responses & Transplant Introduction

Immune Responses & Transplant Introduction

• NUR 251 course aims to cover immune responses and transplantation.

Learning Objectives

• Outline components and functions of the immune system.
• Differentiate between types of immunity and immunity development.
• Explain 5 types of immunoglobulins with patient scenarios.
• Differentiate the 4 types of hypersensitivity reactions based on immunologic mechanisms and resulting alterations.
• Describe clinical manifestations and emergency management of systemic anaphylactic reaction.
• Identify rejection types after transplantation.
• Identify immunosuppressive therapy types and side effects.
• Explain the mechanics of immunosuppressive therapy in organ transplant situations.
• Identify types of transplants and related terminology.

Immune Response

• A complex defense mechanism safeguards against foreign substances.
• Critical for maintaining health.
• When compromised, immune responses can lead to infection or tissue integrity issues.

Normal Immune Response

• Immunity is the body's ability to resist diseases.
• It serves three functions: defense, homeostasis, and surveillance.

Antigens

• Substances that trigger an immune response.
• Most are proteins, but polysaccharides, lipoproteins, and nucleic acids can also act as antigens.
• Unique to each person, allowing the body to recognize itself.

Antibodies

• Immune globulins produced by lymphocytes in response to antigens.
• IgG antibodies are responsible for secondary immune responses, and can cross the placenta.
• IgA antibodies line mucus membranes and protect body surfaces.
• IgM antibodies are responsible for primary immune responses and form antibodies to ABO blood antigens.
• IgD antibodies are present on lymphocyte surfaces and aid in B lymphocyte differentiation.
• IgE antibodies are the major cause of allergic reactions and defend against parasitic infection.

Types of Immunity

• Innate immunity is present at birth and considered a first-line defense with quick response times.
• Acquired immunity, developed over time, can be active and long lasting, or passive and short lived.

Acquired Immunity: Active

• Immunity results from natural contact with an antigen, through actual infection.
• Immunity results from immunization with an antigen contained in vaccines.

Acquired Immunity: Passive

• Immunity is transferred from mother to child via the placenta and colostrum.
• Immunity results from the injection of serum containing antibodies from one person to another.

Organs of Immunity: Central

• Bone marrow produces lymphocytes, red blood cells, and platelets, which eventually migrate to the periphery.
• Thymus differentiates and matures T lymphocytes, shrinking with age.

Organs of Immunity: Peripheral

• Lymph nodes filter foreign material and circulate lymphocytes.
• Tonsils attach and react to ingested or breathed-in foreign antigens.
• The spleen filters foreign antigens and abnormal blood cells, stores recycled iron, and initiates an immune response with B and T lymphocytes.

Cells of the Immune System

• Mononuclear phagocytes include monocytes and macrophages in the blood.
• Lymphocytes produced in bone marrow differentiate into B and T lymphocytes.
• Dendritic cells capture antigens at the site of contact.
• Cytokines are intracellular messengers that direct cells to alter proliferation, differentiation, secretion, or activity.
• Cytokine types include interleukins, interferon, tumor necrosis factor, and erythropoietin.

Lymphocytes: B lymphocytes

• B lymphocytes, known as "B cells," differentiate into plasma cells when activated.
• Plasma cells produce antibodies known as immunoglobulins.
• B lymphocytes are involved in the humeral response.

Lymphocytes: T lymphocytes

• T lymphocytes, known as "T cells," migrate from bone marrow to the thymus and then differentiate.
• T cytotoxic cells (CD8) kill viruses and foreign antigens.
• T helper cells (CD4) help produce cytokines (humoral and cell-mediated).
• T lymphocytes account for long-term immunity and are involved in cellular-mediated immunity.

Natural Killer Cells

• Although the mechanism is not fully understood, natural killer cells are part of innate immunity.
• Large lymphocytes are able to recognize and kill infected cells, tumor cells, and transplanted grafts without prior sensitization.

Immune Reactions: Humoral Immunity

• Humoral immunity is antibody mediated using B cells.
• It uses antibodies to recognize surface antigens.
• Targets bacteria, extracellular viruses, and respiratory pathogens.

Immune Reactions: Cell Mediated

• Cell-mediated uses T-Cells, NK cells, and Macrophages.
• Cell-mediated immunity involves sensitized T cells and cytokines.
• Fights against fungus, intracellular viruses, chronic infectious agents, and tumor cells.

Effects of Aging on the Immune System

• Immunosenescence is the decline in immune response function with age.
• Anergy is an immunodeficient condition marked by lack of reaction to an antigen.
• Aging marked by a higher rate of malignancies, higher rate of infections, increased autoantibodies, thymic shrinking, and decreased immunoglobulins.

Altered Immune Response

• Immunocompetence involves the immune system identifying, inactivating, or destroying foreign substances
• An incompetent immune system makes an individual under responsive, which can result in severe infections, cancers, and immunodeficiency diseases.
• An overreactive immune system results in hypersensitivity disorder

Hypersensitivity Reactions

• Hypersensitivity reactions are alterations in immunocompetence that result in the body overreacting.
• The four types of exaggerated immune responses are:
  • Type I IgE mediated (localized vs anaphylactic)
  • Type II Cytotoxic & Cytolytic Reaction (blood reaction)
  • Type III Immune Complex Reaction (rheumatoid arthritis)
  • Type IV Delayed Hypersensitivity Reaction

Type I- IgE Mediated

• When first exposed to an allergen, IgE antibodies are produced and bind to mast cells and basophils.
• Later exposure triggers degranulation and chemical mediator release to attack target tissues.
• It causes short-acting localized atopic reactions like allergic rhinitis, asthma, atopic dermatitis, and angioedema.

Type I- Anaphylaxis

• Anaphylaxis occurs when chemical mediators are released systemically, unbinding from mast cells and basophils.
• Anaphylaxis can be localized with cutaneous wheal and flare reactions.
• More severe cases can lead to histamine and prostaglandin release which causes vasodilation and increased capillary permeability.
• Serotonin and kinin release is due to smooth muscle contraction, bronchial constriction, and airway obstruction.

Type II- Cytotoxic & Cytolytic Reaction

• Reaction is caused by the direct binding of IgG or IgM antibodies to antigens on the cell surface.
• Causes destruction of erythrocytes, platelets, and leukocytes.
• Involves the compliment system.
• Common causes include hemolytic transfusion reactions by recipient receives ABO incompatible blood from a donor
• Goodpasture Syndrome is antibody mediated autoimmune reaction involving basement membranes

Type III- Immune Complex Reactions

• Soluble antigens combine with IgG & IgM to form antigen-antibody complexes.
• Complexes deposit in the tissue or small blood vessels but cannot be removed by phagocytes.
• Compliment system activation leads to inflammation and destruction of involved tissues.
• Common types include acute glomerulonephritis, rheumatoid arthritis, and post-streptococcal scarlet fever.

Type IV-Delayed Hypersensitivity

• Reaction is a cell Mediated immune response usually within 24-48 hours.
• Sensitized T lymphocytes attack antigens or release cytokines.
• Macrophages & enzymes move to the area, causing tissue damage.
• Commonly seen with contact dermatitis, forming memory cells after exposure to substances that penetrate the skin, causing subsequent reactions.
• Present in latex allergies and Mantoux tests.

Latex Allergy

• Type I reaction occurs as a response to natural latex proteins, happening within minutes, and produces systemic reactions.
• Type IV reaction is contact dermatitis from chemicals in manufacturing latex gloves, occurring within 6-48 hours after exposure.
• Items that contain Latex are Gloves, Tubing, Adhesive Tape, and Oxygen masks,

Diagnostic Tests: Non-Specific

• Non-specific tests include CBC with differential, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and nasal/bronchial secretions for eosinophils.

Diagnostic Tests: Specific

• Specific tests include serum IgE, skin/intradermal or patch testing, genetic testing, and Western blot tests.

Nursing Management

• Allergen recognition and control.
• Education on the use of Epi-Pens.
• Focus on Immunizations.
• Avoid High Risk Behaviors.
• Maintain Infection control measures.
• Conduct an accurate patient history.
• Educating patients about medications such as antihistamines, decongestants, antipruritics, and leukotriene receptor antagonists.

Autoimmunity

• Autoimmunity is defined as an immune response against self.
• The body cannot differentiate self from non-self.
• Conditions can be familial or come in clusters and linked with HLA's (Human Leukocyte Antigens).
• Can be caused by inherited susceptibility genes which cause failure of self-tolerance.
• Can be caused by initiation of autoreactivity by triggers which activate self-reactive lymphocytes.

Immunodeficiency: Primary

• Basic categories include phagocytic defects, B-cell deficiency, T-cell deficiency, and combined B and T cell deficiency.

Immunodeficiency: Secondary

• Factors include age, conditions, drug-induced, malnutrition, stress, and therapies.

Transplants

• Increased success with surgical technique and histocompatibility testing.
• Transplants can involve single or multi-organs transplants.
• Donors can be both living or deceased.
• Transplants can involve entire or partial organs.
• Common types of transplants are cornea, skin, bone marrow and heart valves.

Transplant Rejection

• Occurs as a normal immune response to foreign tissues.
• Three types are
  • Hyperacute which is within 24 hours after transplant with no treatment.
  • Acute which is within 6 months after transplant and is commonly treated with immunosuppressive therapy.
  • Chronic which occurs over several months or years for known or unknown reasons and is irreversible.

Immunosuppressive Therapy

• Maintaining life-long balance between rejection and infection must be achieved.
• Drug groups include Calcineurin Inhibitors, Corticosteroids, Cytotoxic Drugs-Antiproliferative, Monoclonal Antibodies, Polyclonal Antibodies, and other such as Belatacept.