Immunology

Autoimmunity – Definition, Types, Tolerance, Pathogenesis, Mechanisms

Autoimmunity - Definition, Types, Tolerance, Pathogenesis, Mechanisms

What is Autoimmunity? General Features Of Immunologic Tolerance Autoimmunity, encompassing more than 80 different conditions, affects approximately 5% of the population. While each autoimmune disease may have unique characteristics, there are several common features shared among them: Autoimmune diseases can be classified into two broad categories based on the nature of the targeted self-antigens: organ-specific … Read more

Type 1 (Anaphylactic) Hypersensitivity Reaction – Definition, Mechanism, Examples

Type 1 (Anaphylactic) Hypersensitivity Reaction - Definition, Mechanism, Examples

What is Type I Hypersensitivity Reaction? Definition of Type I Hypersensitivity Reaction? Type I hypersensitivity reaction, also known as immediate hypersensitivity, is an exaggerated immune response triggered by the re-exposure to a specific allergen. It involves the rapid release of inflammatory mediators from mast cells and basophils sensitized with IgE antibodies. This type of reaction … Read more

Type II (Cytotoxic) Hypersensitivity – Definition, Mechanism, Examples

Type II (Cytotoxic) Hypersensitivity - Definition, Mechanism, Examples

What is Type II Hypersensitivity? Definition of Type II Hypersensitivity Type II hypersensitivity is an immune response characterized by the destruction of healthy cells mediated by antibodies, specifically IgG or IgM, targeting antigens on the surface of host cells. This antibody-mediated reaction can lead to cell lysis, tissue damage, or loss of function. Mechanism of … Read more

Type III Hypersensitivity – Definition, Types, Mechanism, Examples

Type III Hypersensitivity - Definition, Types, Mechanism, Examples

What is Type III Hypersensitivity? Definition of Type III Hypersensitivity Type III hypersensitivity is an allergic reaction characterized by the accumulation of immune complexes (antigen-antibody complexes) in tissues, leading to inflammation and tissue damage. Types of Type III hypersensitivity reaction Type III hypersensitivity reactions can be categorized into localized and generalized reactions. The manifestation of … Read more

Major Histocompatibility Complex I – Definition, Structure, Mechanism, Functions

Major Histocompatibility Complex I - Definition, Structure, Mechanism, Functions

What is Class I MHC (Major Histocompatibility Complex) molecules? Cellular Distribution of Major Histocompatibility Complex I (MHC I) Major Histocompatibility Complex I (MHC I) Structure The majority of nucleated cells have an assortment of MHC class I proteins. The peptides bound by these MHC class I molecules are typically endogenous, or derived from the breakdown … Read more

Type IV or Delayed-Type Hypersensitivity (DTH)

Type IV or Delayed-Type Hypersensitivity (DTH)

What is Type IV or Delayed-Type Hypersensitivity (DTH)? Definition of Type IV or Delayed-Type Hypersensitivity (DTH) Type IV or Delayed-Type Hypersensitivity (DTH) is an immune response mediated by T cells rather than antibodies, characterized by a delayed onset (usually 24-72 hours) after exposure to an antigen. It involves the interaction of CD4+ T cells, monocytes, … Read more

Major Histocompatibility Complex II (MHC II molecules) – Structure, Mechanism and Functions

Major Histocompatibility Complex II (MHC II molecules) - Structure, Mechanism and Functions

What is Major Histocompatibility Complex II (MHC II molecules)? Cellular Distribution of Major Histocompatibility Complex II (MHC II molecules) Structure of Major Histocompatibility Complex II (MHC II molecules) As stated previously, MHC class II molecules are nearly exclusively located on APCs. The peptides bound by MHC class II are produced from the breakdown of proteins … Read more

Lymph Nodes – Definition, Location, Structure and Functions

Lymph Nodes - Definition, Location, Structure and Functions

What is Lymph Nodes? Definition of Lymph Nodes Lymph nodes are small organs in the lymphatic system that filter lymph and play a critical role in the body’s immune response. Location of Lymph Nodes Size of Lymph Nodes The size of lymph nodes can vary depending on their location within the body. Here are some general guidelines … Read more

Passive Immunization – Definition, Advantages, Disadvantages, Examples

Passive Immunization - Definition, Advantages, Disadvantages, Examples

What is Passive Immunization? Definition of Passive Immunization Passive immunization refers to the direct administration of pre-formed antibodies or immune cells from another individual to provide immediate protection against infectious agents or toxins. Process of Passive Immunization Passive immunization involves the direct transfer of pre-formed antibodies or immune cells from a donor to an individual … Read more

Bone Marrow – Definition, Types, Structure and Functions

Bone Marrow - Definition, Types, Structure and Functions

What is Bone Marrow? Definition of Bone Marrow Bone marrow is the soft tissue found within the cavities of bones that produces various types of blood cells, including red blood cells, white blood cells, and platelets. Location of Bone Marrow The location of bone marrow within the human body is widely distributed, but it undergoes changes … Read more

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