Immunology Lecture Notes Review

Flashcards about the immune system, including innate and adaptive immunity, key immune cells, antigens, antibodies, and hypersensitivity reactions.

What is the general role of the immune system?

Protection from pathogens (viruses, bacteria, fungi, parasites, toxins) and is critically important for survival.

What are the three essential functions of the immune system?

Recognizing pathogens, balancing the response to avoid tissue damage, and not generating a response to self-molecules.

What is the key difference between innate and adaptive immunity?

Innate immunity is rapid and non-specific, while adaptive immunity is slower but provides a pathogen-specific response with memory.

What is the difference between humoral and cell-mediated immunity?

Humoral immunity is mediated by molecules in the extracellular fluid, while cell-mediated immunity involves the activation of immune cells.

What are the physical barriers that represent the first line of defense?

Skin and mucosal surfaces.

What are the key cells and molecules involved in innate immunity?

Phagocytes, antimicrobial peptides, natural killer cells, mast cells, dendritic cells, complement, cytokines, and chemokines.

What are the key cells and molecules involved in adaptive immunity?

T and B cells, antibodies, cytokines, and chemokines.

How do antigen-presenting cells activate the adaptive immune response?

Antigen Presenting Cells (APCs) internalize and display antigen on their surface using Major Histocompatibility Complex (MHC) molecules, activating T cells.

What are the primary lymphoid organs?

Red bone marrow and thymus.

What are the secondary lymphoid organs?

Lymph nodes, spleen, Peyer’s patches, and mucosal tissues.

What occurs in the primary lymphoid organs?

Site of lymphocyte production and maturation.

What occurs in the secondary lymphoid organs?

Site of adaptive immune response and antigen presentation.

What is the role of the lymphatic system?

Transports interstitial fluid (lymph) through the body and supports the circulation of lymphocytes.

What are the functions of the spleen?

Site of B cell activation and maturation, removal of old erythrocytes, and clearance of antibody-coated bacteria.

What are the functions of the red bone marrow?

Hematopoiesis, B cell maturation and selection, and housing long-lived antibody-producing plasma cells.

What are the functions of the thymus?

Generation of mature naïve T cells and T cell selection.

What are the functions of the lymph nodes?

Location of adaptive immune cell activation and antigen presentation.

What are the roles of monocytes and macrophages in the immune response?

Monocytes differentiate into macrophages upon entering tissues, engulf pathogens, release toxic molecules, and release cytokines.

What are the different types of granulocytes?

Neutrophils, eosinophils, basophils, and mast cells.

What is the role of neutrophils in the immune response?

Rapidly enter tissues, phagocytose pathogens, release cytotoxic agents, and release neutrophil extracellular traps (NETs).

What is the role of eosinophils in the immune response?

Clearance of multicellular parasites and involvement in allergic reactions.

What is the role of basophils in the immune response?

Secrete anticoagulants and histamine during hypersensitivity reactions.

What is the role of mast cells in the immune response?

Release anticoagulants and histamine; similar to basophils but are present in the tissues.

What is the role of NK (Natural Killer) cells in the immune response?

Kill abnormal cells (tumor cells, virus-infected cells, transplant cells) by releasing cytotoxic molecules and inducing apoptosis.

What is the role of dendritic cells in the immune response?

Collect antigen in the peripheral tissue and migrate to lymph nodes to activate T cells.

What is the role of T lymphocytes in the immune response?

Recognize antigens via T cell receptors (TCR) and provide specificity for the adaptive immune response; includes CD4+ helper T cells and CD8+ cytotoxic T cells.

What is the role of T Helper cells in the immune response?

Activated by antigen in the context of MHCII and help B cells.

What is the role of Cytotoxic T cells (CTLs) in the immune response?

Activated by antigens in the context of MHCI and kill infected cells.

What is the role of B Lymphocytes in the immune response?

Can bring in antigens and become APCs, eventually becoming plasma cells which are a source of antibodies.

What is the role of Innate Lymphoid Cells in the immune response?

They interact with T cells that help tell the adaptive response what the right type of response is.

What is an antigen?

Any substance capable of generating an immune response, typically a protein component of bacteria or virus.

What is an epitope?

Part of an antigen that is recognized by the immune system.

What are antibodies?

Soluble molecules produced by B cells, highly specific to a particular epitope on an antigen.

What is the role of IgM immunoglobulins?

Primary early response.

What is the role of IgG immunoglobulins?

Highest concentration in blood, neutralizes toxins.

What is the role of IgD immunoglobulins?

Forms BCR.

What is the role of IgA immunoglobulins?

Secreted as a dimer in mucus.

What is the role of IgE immunoglobulins?

Parasite and allergy response.

What are the roles of cytokines?

Regulate growth and proliferation, direct differentiation of cells, and activate/suppress immune cells.

What are the roles of chemokines?

Released from the site of infection to create a concentration gradient, allowing immune cells to migrate into the area.

Define allergy.

One of the types of hypersensitivity reactions that follows an immune response to an otherwise innocuous antigen.

What is an allergen?

An innocuous antigen that causes the allergic reaction.

Define atopy.

Genetic predisposition to develop allergy.

What are the four types of hypersensitivity reactions?

IgE-mediated, Cytotoxic reactions (IgG), Immune complex-mediated (IgG), Cell-mediated hypersensitivity (Th1, Th2, CTL).

What is the general timing of a Type 1 hypersensitivity reaction?

2-30 minutes.

What is the general timing of a Type 2 hypersensitivity reaction?

5-8 hours.

What is the general timing of a Type 3 hypersensitivity reaction?

2-8 hours.

What is the general timing of a Type 4 hypersensitivity reaction?

24-72 hours.

What events trigger a Type 1 hypersensitivity reaction?

Cross-linking of IgE antibody on mast cells, mediators are released.

What events trigger a Type 2 hypersensitivity reaction?

Humoral antibodies (IgG) injure self cells by targeting them for phagocytosis or lysis.

What events trigger a Type 3 hypersensitivity reaction?

Immune complexes deposit in small blood vessels activating complement pathways.

What events trigger a Type 4 hypersensitivity reaction?

T lymphocytes (CD8 or CD4) cause cell death and tissue injury.

What is the first step in allergen-induced inflammation?

Dendritic cells capture allergens, migrate to lymph nodes, and present the allergen to naïve T cells.

What is the second step in allergen-induced inflammation?

Naïve CD4+ T cells differentiate into Th2 cells in the presence of cytokines such as IL-4 and IL-13.

What is the third step in allergen-induced inflammation?

Th2 cells secrete IL-4, inducing B cells to switch from producing IgM to IgE.

What is the fourth step in allergen-induced inflammation?

IgE binds to high-affinity receptors (FCERI) on mast cells, sensitizing them to the specific allergen.

What is the fifth step in allergen-induced inflammation?

Upon re-exposure to the allergen, cross-linking of IgE on mast cells triggers their activation.

What is the sixth step in allergen-induced inflammation?

Activated mast cells release histamine, cytokines, and other mediators, leading to inflammation.

List key cytokines related to allergic inflammation.

IL-4 induces IgE production and Th2 differentiation; IL-5 recruits and activates eosinophils; IL-13 enhances mucus production and airway hyperresponsiveness; IL-9 promotes mast cell proliferation and survival.

List examples of anti-inflammatory medications.

Salbuterol (bronchodilator), Inhaled Corticosteroids (anti-inflammatory), Omalizumab (anti-IgE), Mepolizumab (Anti-IL5).

Define Asthma.

Chronic inflammatory disease of the airways, reversible airflow obstruction.

What are major characteristics of asthma?

Inflammation of the airway; airway obstruction; enhanced bronchial responsiveness; remodeling.

What is Type 2 inflammation?

Activation of Type 2 polarized CD4+ T cells (TH2 cells) and production of cytokines including IL-4, IL-5, IL-9 and IL-13.

Explain a sensitization of allergens related to asthma.

Dendritic cells present allergen to naïve T cells, which repolarize to TH2 cells, TH2 cells trigger B cells to produce allergen-specific IgE.

What are the immediate manifestations of asthma?

Mast cell/IgE mediated.

What are the late manifestations of Asthma?

TH2 cell mediated.

What are the key cytokines related to late asthma manifestations?

IL-4, IL5, IL-33) .

Monoclonal antibodies: anti-IL-5, anti-IL-4R, anti-IgE, Oxime.

What are other treatments of Type 2 inflammation?

What are some complications of asthma?

Irreversible loss of lung function. Airway remodeling.

What causes asthma?

Genetic, pollution, allergens, hygiene, infections.