Understanding the Immune System

The Immune System

• It is a collection of structures and processes protecting against diseases and damaging foreign bodies
• A functioning system is essential for survival, identifying viruses, bacteria, and parasites
• It guards against disease and tissue damage
• Immune cells are concentrated in blood and lymphatic tissue
• The system has defense against invading organisms
• The system cleans up and removes damaged tissue
• Surveillance identifies and destroys abnormal body cells

Main Components of the Immune System

• Lymph Nodes are a key component
• Spleen is also a key component
• Bone Marrow is a major component
• Lymphocytes, which consist of B-cells, T-cells, and Helper T-cells, are major components
• B-cells make antibodies that attack toxins
• T-cells kill cells infected with pathogens or damaged cells
• Helper T-cells determine immune responses to particular pathogens
• Thymus is another major component
• Leukocytes are also.

Why We Need the Immune System

• To protect us from invaders known as pathogens
• It defends against external threats
• Bacteria and viruses included
• It safeguards against pollution
• It helps with allergies to pets and dust
• It also defends against internal threats

Timing of Immune System

• The immune system starts developing in utero, but the exact timing of when it becomes active is unknown
• The immune system is always working
• Everyone has an immune system

First Line of Defense - Non-Specific & Innate Immunity

• It uses mechanical and chemical barriers
• Skin and mucous membranes are first line
• HCL acid is first line
• Tears and saliva are first line
• Cilia are a barrier
• Wax is a defense

Normal Microbiome

• Body surfaces are colonized with bacteria and fungi unique to the location and individual
• It does not cause disease if the immune system is working
• An opportunistic infection can occur if an immune system is not working

Second Line of Defense - Non-Specific & Innate Immunity

• Phagocytes are WBCs that eat and destroy pathogens
• Inflammation responds to infection and injury resulting in erythema, edema, heat, and pain at the site of injury
• Pyrogens travel to the hypothalamus producing a fever
• Cytokines stop the spread of viruses to new cells
• Cytokines include interferons and interleukins
• Complement Proteins enhance the action of antibodies

Phagocytosis

• Neutrophils and macrophages are the two most important phagocytes

Inflammation

• The body attempts to self-protect and remove harmful stimulation to promote healing
• Infections, wounds, and tissue damage need an inflammatory response to heal
• Chronic inflammation can cause several diseases and conditions

Wound Healing Phases

• Inflammatory phase begins when the wound develops, lasting 4-6 days, marked by oedema, erythema, inflammation and pain
• Healing process triggered
• The immune system works to prevent microbial colonization
• Proliferative phase lasts another 4-24 days as granulation tissue fills the wound
• Fibroblasts lay collagen in the wound bed strengthening new granulation tissue
• Wound edges begin to contract
• Epithelial cells migrate from the wound margins
• Maturation phase lasts 21 days-2 years
• The length of time depends on complicating factors: duration of wound, patient comorbidities, and wound infection status
• The filled-in wound is covered and strengthened
• Scar tissue forms

Dysfunctional Wound Healing

• It can cause impaired collagen matrix assembly, Keloid
• It can cause hypertrophic scar
• It can cause impaired epithelialization, and impaired contraction
• It can cause wound dehiscence

Immunity - Third Line of Defense - Specific & Acquired

• Lymphocytes take out specific pathogens
• There are two types of lymphocytes, which must see the pathogen first to respond
• They both develop memory to what they have destroyed
• T-cells come from the thymus gland and recognize what is wrong and targets cells
• B-cells come from bone marrow, produce antibodies that bind to foreign material

Types of Immunity

• Active immunity is gained by actively engaging with an antigen through invasion or vaccination
• An example is building resistance to a disease and fighting of a cold
• Passive immunity is gained by receiving antibodies made outside the body by another person, animal, or recombinant DNA
• Breastfeeding is an example

CD Molecules

• Surface molecules expressed on cells of the immune system
• Play key roles in immune cell-cell communication
• Essential markers for the identification and isolation of leukocytes and lymphocyte subsets

Classes of Immunoglobins

• There are 5 classes of all immunoglobins(antibodies)
• They have specificity for a specific antigen
• IgG is the most abundant, accounts for most of the protective activity against infections
• IgA is found in blood and body secretions

Disorders of the Immune System

• Complications arise when the immune system does not function correctly
• These include allergies, immune deficiency, autoimmune diseases, sepsis, and cancer
• It can have minor effects such as allergies
• It can have extensive effects such as cancer, and genetic disorders

Hypersensitivity

• The body responds to a particular substance in an exaggerated fashion not typical
• It results in inflammation and destruction of healthy tissue
• It may be immediate or delayed
• There are 4 produced types of reactions

Types of Hypersensitivity Reactions

• Type I: Immediate (IgE Mediated), which results in hay fever, anaphylaxis
• Type II: Tissue Specific where IgG or IgM reaction with an antigen on the cell results in lysis; blood transfusion reaction
• Type III: Immune Complex Mediated which means antigen-antibody complexes accumulate and become deposited in tissues
• Autoimmune disorders results
• Type IV: Cell Mediated Delayed processing of the antigen by macrophages; TB test, transplant reaction and contact dermatitis

Type 1 Immediate Hypersensitivity Allergies:

• Body makes a hyper-response to a foreign material
• Can induce a localized response with itchy eyes, runny nose,scratchy throat, hives and or digestive issues
• Can induce systemic response such as Anaphylactic shock, Respiratory and or circulatory collapse

Type 2 Hypersensitivity - Cytotoxic

• *Bloodtransfusion

• Reaction

• Blood types are determined by the protein you have on your blood cells

Autoimmune Disorders

• Normal defenses become self-destructive perceiving the self as foreign
• The causes are unclear, and affect women more often than men
• It can affect any tissue in the body
• Characterized by remissions and exacerbations
• Stress can trigger exacerbations
• Diagnosing is difficult
• Treatment includes meds and managing stress

Systemic Lupus Erythematosus

• It is a chronic inflammatory autoimmune disorder, affecting connective tissue
• B cells activated for unknown reasons to produce AB and AG
• These result in immune complexes (IC)
• The immune complex fight against the body's own tissue

Diagnostic Criteria for Systemic Lupus Erythematosus

• Butterfly rash over the cheeks of the face
• Skin rashes and Photosensitivity, with mucous membrane ulcers
• Joint inflammation and Renal Abnormalities
• Pain, fatigue and Renal abnormalities
• Pleuritis or pericarditis [chest pain].

Systemic Lupus Treatment

• Prognosis improves with early diagnosis and treatment
• Diagnose with Inflammation markers: CRP and ESR
• Treatment is for symptoms only as there is no cure
• Include stress management, health promotion behaviors, and frequent rest

Transplants

• A graft is any tissue taken from one body part and used in another to match tissue antigens for success
• Donor sources include living or cadavers
• There are different graft types: autograft on same person, isograft twins, allograft same species, xenograft different species

Transplant Reactions

• Caused by failing organs
• Non adherence can also cause
• Rejection is rejection based on timing
• Hyper-acute reactions are immediate
• Acute reactions in 4 days to 3 months
• Chronic [most common] reactions in 4 to months years

Rejection Reactions

• The host fights grafts
• Grafts may fight the host
• One must identify is quickly
• Failure of organ is first sign that must be prevented with Immunosuppressive Therapy

Immunodeficiency

• Occurs when response is absent leaving the patient open to contract or spread of infection
• This may be caused from immune defect/genetic loss or developed throughout life
• Opportunistic Infection can be result
• Diagnosis - measure Imunoglobin levels
• Treatment must start with Gamma Globulins

Autoimmune Disorders

At Risk Individuals for Immune Dysfunction

• Very young and very old, or if have poor nutrition
• Can be caused by Impaired skin integrity, Circulatory issues, and Alterations in normal flora due to antibiotic therapy
• Can happen with Chronic diseases
• Can be from to Corticosteroid and Chemotherapy
• From Smoking, Alcohol consumption and Immunodeficiency states

Strengthening the Immune System

• Increasing fluid intake and diet
• Increasing antioxidants
• Regulate Sleep
• Get Sunshine
• Reduce stress
• Avoid sugar and or coffee

Replacement Therapies for Immune deficiencies

• Gamma Globulin Therapy
• Transplantation and Transfusion, is needed to fix