Immunology Overview and Concepts

IgG is the most abundant immunoglobulin in the blood.

Plasmapheresis is a procedure that removes excess antibodies from the blood, often used to treat autoimmune diseases.

IL-2 is a critical cytokine for the activation and multiplication of cytotoxic T cells, helping them fight infected cells.

Class II MHC molecules are found on antigen-presenting cells (APCs), which display antigens to T cells, initiating an immune response.

Cytotoxic T cells trigger apoptosis, a programmed cell death, in targeted cells.

Leukocytes, especially dendritic cells, produce interferons when a viral infection is detected.

IgG is the only antibody that can cross the placenta from mother to baby, providing passive immunity in newborns.

IgA is found in breast milk and protects the baby's digestive tract.

The ability of the immune system to recognize and respond to specific pathogens or foreign substances. This branch of the immune system develops over time, learning to recognize and target new threats.

These specialized cells, part of the innate immune system, are the first line of defense against pathogens. They engulf and destroy invading microbes.

Molecules found on the surface of pathogens that are recognized by the immune system. These patterns are unique to pathogens, helping the immune system distinguish 'self' from 'non-self'.

A type of immune cell that plays a crucial role in recognizing PAMPs. Once activated, they initiate the immune response by releasing signaling molecules called cytokines.

The complex process that involves a cascade of proteins, ultimately leading to the destruction of pathogens. This system acts as a key component of the innate immune response.

The process by which foreign antigens are taken into cells and broken down, presented to immune cells to trigger an immune response.

The process by which the immune system learns to tolerate self-antigens and prevent autoimmune reactions. This important process occurs during development in the thymus.

A type of immune cell that helps regulate the immune response by suppressing other cells. They play a crucial role in preventing autoimmune diseases.

A condition where the immune system attacks the body's own tissues, leading to damage and inflammation. This can affect various organs and systems.

A type of immune response that involves the production of antibodies (immunoglobulins) by B cells to neutralize pathogens.

A type of immune response that involves T cells directly attacking infected cells or pathogens. This response targets intracellular pathogens.

The process in which the immune system encounters an antigen for the first time and initiates a response. This response is slower but lays the foundation for future responses.

The rapid, strong and specific immune response that occurs upon subsequent exposure to an antigen the immune system has already encountered. This response is much faster and more effective than the primary response.

A type of immune cell that is responsible for producing antibodies. They are key players in humoral immunity.

The Fc fragment of an antibody interacts with receptors on innate immune cells, such as macrophages and neutrophils, triggering their activation and leading to immune responses like phagocytosis and inflammation.

NK cells are lymphocytes that can directly kill target cells without engulfing them. Instead, they induce apoptosis in infected or cancerous cells.

Antigen-presenting cells (APCs) express MHC Class II molecules and co-stimulatory signals, like CD80, which are required for the proper activation of naive CD4+ T cells. These interactions initiate the adaptive immune response.

The B-cell receptor (BCR) is the primary receptor on B lymphocytes responsible for recognizing and binding to T-dependent antigens. This interaction initiates the activation of the B cell.

Plasma cells are mature B cells that are specialized for producing and secreting antibodies. These antibodies are the key effector molecules of the humoral immune response.

The classical complement pathway is activated by the C1 complex which binds to immune complexes, such as antigen-antibody complexes. This activation starts a cascade of events leading to the lysis of pathogens and inflammation.

Regulatory T cells (Treg) are specialized lymphocytes that help suppress excessive immune responses, maintaining tolerance and preventing autoimmune reactions. They contribute towards maintaining immune homeostasis.

The CD4 molecule, expressed on helper T cells, binds to MHC Class II molecules presented by antigen-presenting cells. This interaction is fundamental for the activation and differentiation of helper T cells.

IgA is the major immunoglobulin found in mucosal secretions, such as those in the respiratory tract, gut, and genital tract. It provides a first line of defense against pathogens entering these mucosal surfaces.

The immunological synapse is the specialized contact zone formed between a T cell and an antigen-presenting cell. At this synapse, antigen recognition, signal transduction, and activation of immune cells takes place.

Cytotoxic T cells (T-killers) recognize and destroy infected cells, often those infected with viruses. They interact with MHC Class I molecules on the surface of infected cells to initiate the destruction process.

Type I interferons (alpha and beta) are cytokines that are produced in response to viral infections. They have a broad range of antiviral effects, including inhibiting viral replication and activating the immune system.

NK cells are activated when they detect cells lacking MHC Class I molecules. This absence can be indicative of infected or cancerous cells, triggering the NK cell's attack.

CD19 is a surface marker specifically found on B lymphocytes, often used in identifying and isolating them for research and therapeutic purposes.

Th2 cells are a type of helper T cell that play a crucial role in the humoral arm of the immune response, particularly in allergic responses. They help activate B cells to produce antibodies, especially IgE.

Light microscopy is a type of microscopy that uses visible light to illuminate and magnify the specimen, allowing visualization of the different types of leukocytes (white blood cells) in blood smears.

CD3 is a surface marker receptor found on T lymphocytes, while CD19 is found on B lymphocytes. These markers are used to distinguish between these two types of lymphocytes.

Serum immunoglobulin levels (like IgG, IgM, IgA, etc.) are a reflection of the antibody-mediated humoral immune system. High levels indicate active antibody production.

ELISA (Enzyme-Linked Immunosorbent Assay) is a technique that utilizes labelled antibodies or antigens to detect specific substances in a sample. It works by enzyme activity causing a color change for detection.

In an ELISA, the antigen or antibody is labelled with an enzyme, which produces a color change that is measurable and indicates the presence of the targeted substance.

The EAC (Erythrocyte Antibody Complement) rosette test is a method for determining the absolute number of lymphocytes in a blood sample, particularly T cells, by their ability to bind sheep erythrocytes.

Immediate-type hypersensitivity (IHT), also known as Type I hypersensitivity, is a rapid allergic reaction that is mediated by IgE antibodies. This reaction occurs within minutes of exposure to the allergen.

Delayed-type hypersensitivity (DHT), also known as Type IV hypersensitivity, is a cell-mediated immune response that involves T lymphocytes, primarily CD4+ T cells. It develops over a period of 24-72 hours after exposure to the antigen.

Hypersensitivity reactions are characterized by tissue damage caused by an excessive or inappropriate immune response to an antigen.

Anaphylaxis is a severe, life-threatening allergic reaction that can happen quickly after exposure to an allergen. Symptoms can include swelling, difficulty breathing, and a drop in blood pressure.

Delayed-type hypersensitivity (DHT) involves T lymphocytes (T cells) in the immune response. These cells recognize specific antigens and initiate a reaction.

Hemolytic disease of the newborn (HDN) occurs when an Rh-negative mother develops antibodies against Rh-positive red blood cells of the fetus. This can happen if the mother is exposed to fetal blood during pregnancy or delivery.

Interleukin-5 (IL-5) is a cytokine that stimulates the activation and recruitment of eosinophils, a type of white blood cell involved in allergic reactions.

The diversity of antibodies is generated through a process called recombination, where gene segments are rearranged during B cell development leading to a vast array of antibody specificities.