Diseases of the Immune System - Nelson Flashcards
What are the two branches of the Adaptive Immune System?
Humoral Immunity
Cellular Immunity
What is the function of the immune system?
To protect against harmful microorganisms and cellular agents (malignant cells)
Define Immunodeficiencies
Disorders with decrease or loss of immune function, either acquired or congenital
What are Hypersensitivity Reactions and what are the 2 types of having TOO MUCH immunity?
Disorders with pathologic immune responses or reactions
Allergic Reactions
Autoimmune Reactions
Type I Hypersensitivity
Too much IgE crosslinking in response to environmental antigen leading to mast cell and basophil release of histamine, causing synthesis of prostaglandins and leukotreines, such as hay fever, asthma, hives, food allergies, and eczema.
Type II Hypersensitivity
IgG or IgM Mediated Autoimmunity due to antibodies that react against self, such as hemolytic disease of maternal antibodies reacting to fetal RBCs, Myasthenia Gravis (AChR antibodies), and Good Pasture’s Syndrome (Basement membrane antibodies causing nephritis).
Type III Hypersensitivity
Immune complexes of antigen and antibody that get stuck in small vessels, such as the kidneys, joints, pleura and skin. Complement is activated to respond to the antigen-antibody complex and healthy tissues are destroyed in the process, which happens in Lupus (making antibody to own DNA) and RA (making antibody to antibody); serum sickness, necrotizing vasculitis.
Type IV Hypersensitivity
Cell-mediated hypersensitivity caused by activated CD4+ Th1 T-Cells (autoimune or innocent bystander injury); Contact hypersensitivity, TB reactions, Granulomatous hypersensitivity
Humoral Immunity
B-cells that protect extracellular spaces release antibodies into bodily fluids.
Cell-Mediated Immunity
T-cells that survey surfaces of cells, looking for mutated cells or parasites.
Define Innate Immunity
Pre-existing defense mechanisms present prior to infection
Define Adaptive Immunity
Reactive immune mechanisms that are stimulated by microbes or other foreign antigens
Function of B Lymphocytes
Neutralization of microbe, phagocytosis, complement activation
Function of Helper T Lymphocytes (CD4+)
Activation of macrophages
Inflammation
Activation (proliferation and differentiation) of T and B lymphocytes
Function of Cytotoxic T Lymphocytes (CD8+)
Killing infected cells
Function of Regulatory T Lymphocytes
Suppression of Immune Response
Function of Natural Killer cells
Killing infected cells
Define Generative (Primary) Lymphoid Organs
Sites where T (Thymus) and B (Bone Marrow) lymphocytes mature
Define Peripheral (Secondary) Lymphoid Organs
Site where the adaptive immune response is initiated (lymph nodes, spleen)
Class I MHC Molecules
coded by HLA-A, HLA-B, and HLA-C genes and display antigens to CD8+ T-cells and NK cells
Class II MHC Molecules
coded by HLA-DP, HLA-DQ, HLA-DR genes and display antigents to CD4+ T-cells
What are two uses for HLA testing?
1) determine disease risk
2) transplantation workup
What is light chain restriction?
Monoclonal B-cells typically express only one type of immunoglobulin, either kappa or lambda.
How can monoclonal light chain restriction be detected?
Flow cytometry - should be 1.5 kappa to lambda
Serum protein electrophoresis
Immunofixation electrophoresis
Kappa and lambda in situ hybridization - staining looking for proportions
What are the 5 pillars of cancer treatment?
Surgery Chemotherapy Radiation Therapy Molecular Targeted Therapy Imatinib and Trastuzumab Target cancer cells by homing in on specific molecular changes seen primarily in those cells Immunotherapy T-cells to attack the tumor
Define Hypersensitivity Reactions
Sensitization to previous exposure to antigen and when re-exposed, pathologic immune reactions ensue with excessive, injurious reaction to the antigen
What does a hypersensitivity reaction usually result from?
Imbalance between effector mechanisms of immune response and control mechanism to limit response
What do eosinophils release in a type I hypersensitivity reaction?
Major Basic Protein and Eosinophil Cationic Protein = Toxic to epithelial cells
Define Atopy
Predisposition of developing immediate hypersensitivity reactions; 50% correlated with positive family history; higher serum levels of IgE and more Il-4 producing Th2 cells
Describe the immediate type I hypersensitivity reaction
Exposure to allergen –> Th2 response and IgE production –> IgE binds to Fc on Mast Cells –> Re-exposure to allergen leads to mast cell degranulation
Causes: Vasodilation
Vascular Leakage
Smooth Muscle Spasm
Describe the late phase type I hypersensitivity reaction
Eosinophil infiltration with neutrophils and T-cells
Causes: Leukocyte Infiltration
Epithelial Damage
Bronchospasm
Describe immediate hypersensitivity reactions with non-atopic allergies
Exercise or temperature induced, not mediated by T-cells or IgE
Immediate Type I Hypersensitivity Systemic Anaphylaxis
Life threatening systemic allergic reaction with falling BP, vascular shock, bronchospasm, laryngeal edema and difficulty breathing due to massive mast cell activation
What are the two mechanisms for T-cell Mediated Type IV Hypersensitivity?
CD4+ T-Cell Mediated Inflammation
CD8+ T-Cell Mediated Cytotoxicity
Define Graulomatous inflammation
A distinctive pattern of chronic inflammation via strong activation of T-cells leading to activated macrophages resulting in tissue injury.
What is a granuloma?
A focus of chronic inflammation consisting of a microscopic aggregation of macrophages that are transformed into epithelial-like cells called histiocytes; may also fuse to form multi-nucleated giant cells
What causes granulomas to form?
Immune reactions or reaction to foreign material
Foreign Body Granulomas
See foreign material within histiocytes or giant cells
Caseating Granulomas
Granulomas that induce cell-mediated immune response with central necrosis; usually associated with infection (mycobacterial and fungal infections)
Non-Caseating Granulomas
Granulomas that induce cell-mediated immune response without central necrosis (sarcoidosis, Crohn’s disease)
