Allergy Development and Responses Quiz

Disorders in Immunity

• Disorders in immunity are studied to understand disease states associated with under-reactivity and over-reactivity of the immune response.
• Types of disorders include: allergy/hypersensitivity, autoimmunity, immunodeficiency, and cancer. These are interconnected as disorders affecting one can affect others.

The Immune Response

• The study of disease states associated with under-reactivity and over-reactivity of the immune response.
• Allergy/Hypersensitivity: exaggerated, misdirected immune responses to an allergen (antigen).
• Autoimmunity: abnormal responses to self-antigens.
• Immunodeficiency: deficiency or loss of immunity.
• Cancer: both a cause and effect of immune dysfunction.

Immune System Disorders

• Describes reactions that can lead to diseases in the immune system.
• Overreactions (Allergies and Hypersensitivities): Type I (immediate), Type II (antibody-mediated), Type III (immune complex), Type IV (cell-mediated).
• Underreactions and Loss of Immune Function: lack of T-cell surveillance leading to cancer cell survival; lack of T cells, B cells (or both) compromises the immune system.

Allergy/Hypersensitivity Reactions

• Classification of Immunopathologies caused by overreactions to antigens.
• Types include: Immediate, Antibody-mediated incompatibilities, Immune complex diseases, and Cell-mediated hypersensitivities, each with examples and systems involved.

Type I Allergic Reactions

• Allergies share a similar physiological mechanism; generally immediate in onset and associated with exposure to specific antigens.
• Severity levels: chronic local allergy (e.g., hay fever, asthma) vs. systemic, explosive reaction (involving airway obstruction and circulatory collapse).
• Factors that affect allergy onset include familial predisposition, age, infection, and geographic area. Atopic allergies may be lifelong or ‘outgrown’, potentially developing later in life.

Nature of Allergens and Their Portals of Entry

• Allergens have immunogenic characteristics.
• Allergens typically enter through epithelial portals, like respiratory, gastrointestinal, or skin.
• The organ where the allergic reaction occurs may not be the same as the entry portal.

Common Allergens, Classified by Portal of Entry

• A table categorizing common allergens (e.g., inhalants, ingestants, injectants, contactants) based on their entry route into the body.

Stages in the Development of Allergy

• Primary contact/Sensitization: Initial allergen exposure; generally no signs or symptoms. Dendritic cells activate TH cells in lymph nodes. Interaction between TH and B cells produces plasma cells – which make IgE that attaches to mast cells and basophils. Priming the immune system.

• Subsequent Exposure to Allergen and Provocation: If the same allergen is again encountered, it goes directly to previously primed mast cells leading to degranulation; release of allergic mediators resulting in systemic distribution & symptoms in various organs.

Role of Mast Cells and Basophils

• Ubiquitous location in tissues.
• Mast cells in connective tissue, abundant in lungs, skin, GI, and genitourinary tract.
• Basophils circulate in blood, migrate into tissues.
• Each mast cell can bind many IgE; Contains physiologically active cytokines, histamine, etc.
• They degranulate/release contents in response to allergens.

Cytokines, Target Organs, and Allergic Symptoms

• Chemical mediators released by mast cells and basophils cause allergic symptoms alone or in combination affecting skin, upper respiratory tract, Gl tract, and conjunctiva (causing rashes, itching, redness, rhinitis, sneezing, diarrhea, and shedding tears)
• Target systemic tissues including smooth muscles, mucous glands, and nervous tissue causing blood pressure and respiration changes.

Main Chemical Mediators

• Histamine: most profuse and fastest acting; stimulates smooth muscle, glands and eosinophils. Response to chemical depends on location.
• Serotonin: similar effects as histamine.
• Leukotrienes ("slow reacting substance of anaphylaxis"): cause prolonged bronchospasm, vascular permeability, and mucus secretion (asthma).
• Prostaglandins: powerful inflammatory agents, regulate smooth muscle contraction.
• Bradykinin: causes prolonged contraction of bronchioles, dilation of peripheral arterioles, increased capillary permeability, and mucus secretion.

Reactions to Inflammatory Cytokines

• Effects of chemical mediators on various parts of the body (in response to inflammation)
• Reactions such as headache, dilated blood vessels, wheezing, difficulty breathing, coughing, etc., in various organs, indicating a systemic reaction.

Diseases Associated with Type I Allergy

• Atopic diseases (e.g., hay fever, rhinitis, asthma, atopic dermatitis, food allergies).
• Symptoms like: nasal congestion, breathing difficulties, skin rashes or itchy skin, gastrointestinal problems, and in extreme cases, anaphylaxis.
• Drug allergies are also significant, affecting any tissue, severity from mild to potentially fatal.
• Includes Anaphylaxis, with symptoms like itching, sneezing, difficult breathing, prostration, convulsions, and potential death, occurring in two types: cutaneous and systemic.

Anaphylaxis

• A reaction of an animal injected with foreign protein.
• Symptoms include itching, sneezing, difficult breathing, prostration, convulsions, and possible death.
• Two types in humans: cutaneous anaphylaxis (wheal and flare reaction) and systemic anaphylaxis (anaphylactic shock).

Diagnosis of Allergy

• Skin testing is important to distinguish between allergies and infections.

Environmental Allergens

• Lists common allergens based on their route of entry into the body.

Treatment and Prevention Methods

• Avoiding the allergen is the initial step.
• Corticosteroids inhibit IgE production and T-cell activity.
• Cromolyn stabilizes mast cell membranes.
• Antihistamines counteract cytokine effects on smooth muscle.
• Monoclonal drugs inactivate IgE.
• Desensitization therapy involves injecting allergens to stimulate IgG production, preventing IgE-allergen binding

Type II Hypersensitivities

• Reactions which lead to lysis of foreign cells involving antibodies and complement.
• Transfusion reactions (ABO blood groups and Rh factor) can also cause hemolytic disease of the newborn.

Human ABO Antigens and Blood Types

• Four distinct blood types (A, B, AB, and O) based on inherited glycoproteins on red blood cells.
• Individuals with Type O blood lack A and B glycoproteins; other tissue cells can also carry A and B antigens.
• A table (Table 16.3) displays the characteristics of ABO blood groups, including the antigens present/absent in each blood type and the antibodies found in the plasma.

Antibodies Against A and B Antigens

• Body produces antibodies against different antigens (e.g., Type A contains antibodies that react to B antigens).
• This is a factor in transfusion reactions, indicating why certain blood types cannot be mixed.

Interpretation of Blood Typing

• Agglutination test results are shown with examples (blood is labeled as type A, AB, B, or O based on the reactions with anti-A and anti-B sera).

Transfusion Reactions

• Occur when incompatible blood types are mixed in a transfusion.
• The process of incompatible blood mixing results in clumping of red-blood cells and triggering of the complement cascades causing hemolysis.

Hemolytic Disease of the Newborn

• Rh incompatibility between mother and fetus, especially concerning in subsequent pregnancies.
• Fetal red blood cells can leak into the mother's blood stream and sensitizes the mother's immune system to the Rh factor causing a reaction with subsequent Rh positive pregnancies.

Type III Hypersensitivity

• Reaction of soluble antigen with antibody, causing deposition of the resulting complexes in tissues (basement membranes).
• Localized or systemic responses. Examples: Arthus reaction, serum sickness.

Pathogenesis of Immune Complex Disease

• Describes the stages of formation and action on tissues/organs leading to disease.

Immunopathologies Involving T Cells

• Type IV Hypersensitivity: delayed hypersensitivity reactions that manifest days after exposure to an antigen. In type IV, T cells respond to antigens on self or transplanted tissues which include problems like delayed allergic reactions, contact dermatitis, and graft rejection.

Contact Dermatitis

• Reactions with a delay in manifesting days after exposure to antigens/allergens causing injury/inflammation. This is a skin reaction to chemicals; the exposure to the chemical triggers a response in the immune system. This includes the processes from initial contact to the reaction, including steps like absorption of the chemical, dendritic cells recognizing the chemical, and T-cell activation.

T Cells and Organ Transplantation

• Explains host rejection of transplanted tissues; graft destruction from cytotoxic T cells of the recipient. This includes both host rejection of the graft and graft rejection of the host tissues.

Classes of Grafts

• Different types of grafts categorized based on MHC similarity between donor and recipient: autografts (self-to-self), isografts (identical twins), allografts (different individuals of the same species), xenografts (different species). This includes methods to prevent rejection, like tissue typing and mixed lymphocyte reactions.

Autoimmunity

• Situations where the immune system attacks the body's own tissues.
• This can take a systemic or organ-specific form. Examples: systemic lupus erythematosus, rheumatoid arthritis, endocrine autoimmunities, myasthenia gravis, and multiple sclerosis. Genetic and environmental factors can influence susceptibility.

The Origins of Disease

• Theories of auto-immunity, like sequestered antigen theory (some tissues are immunologically privileged during development), forbidden clones (some T cells are not exposed to self-antigens), and molecular mimicry (microbial antigens resemble self-antigens).

Autoimmune Diseases

• A table summarizing a variety of autoimmune diseases with associated targets and characteristics.

Systemic Autoimmunities

• Discusses systemic lupus erythematosus (SLE) leading to inflammation and rheumatoid arthritis (RA) leading to joint damage affecting lungs, eyes, skin, and nervous systems. Includes the symptoms of SLE and RA.

Endocrine Glands Autoimmunities

• Autoimmune disorders specifically affecting endocrine glands/hormone production and affecting thyroid (Graves' and Hashimoto's), pancreas (I diabetes). Lists symptoms for each endocrine issue.

Neuromuscular Autoimmunities

• Disorders affecting the muscles and nerves: Myasthenia gravis, and Multiple sclerosis. Includes the symptoms for each disease.

Immunodeficiency Diseases

• Describes the absence or dysfunction of components of the immune response system (B and T cells, phagocytes, and complement).
• Separates primary (congenital) and secondary (acquired) deficiencies. Includes examples and causes.

Primary Immunodeficiencies

• A table giving detailed information about various primary immunodeficiencies – including genetic defects, characteristics and treatment. Includes examples and their symptoms.

The Immune System and Cancer

• Immune surveillance: The body's systems keeping an eye out for and eliminating cancer cells through their innate/adaptive immune system.
• The potential for abnormal cell growth, self-contained or cancerous growths, errors in cell division leading to mutations (e.g., mitosis errors, genetic damage, oncogene activation, retroviruses), and the implications for disease development. Including specifics like tumor classification (non-spreading/self-contained and cancerous). Immunity and cancer.

Medical Moment: Candidiasis

• Candida albicans is a ubiquitous yeast (dimorphic) and can be an opportunistic infection in the body.

Pathogenesis of Candidiasis

• Virulence factors include adherence molecules and acid proteases/phospholipase. Conversion to hyphal forms makes them better at penetrating tissues. Includes details about factors that contribute to the spread of the infection

Epidemiology of Invasive Candidiasis

• Risk factors for invasive candidasis include weakened immune systems, broad spectrum antibiotics, and exposure to the fungus, including specific examples of compromised systems in susceptible people.

Epidemiology of Invasive Candidiasis - continued

• Common fungal infection that affects immunocompromised people. Often, 90% of HIV positive patients not undergoing HAART therapy eventually develops oropharyngeal candidiasis and disseminated candidasis mortality rates of 25-30%. Candida is commonly found in fecal flora of almost 40-65% of people, including statistic information.

Drug-Resistant Candida Species

• Significant threat, particularly in hospitalized populations; 2017 data showing significant cases and deaths of individuals due to resistance to antibiotic/drugs that are important to keep the fungus in check. Includes statistic information about cases and deaths.

Signs and Symptoms of Candida Infections

• Systemic, GI, and cutaneous infections with typical signs/symptoms including fever, organ involvement, and skin problems. Symptoms can range from mouth sores to widespread health complications.  Includes detailed symptoms for each type of infection.

Treatment for Candida Infections

• Treatment options for systemic vs. superficial infections detailed, including specific drugs like fluconazole.

Test your knowledge on the various stages of allergy development, including primary sensitization, mast cell functions, and the physiological responses during allergic reactions. This quiz covers common symptoms, diagnostic methods, and specifics about drug allergies versus other allergies.