Autoimmune Disease- Definition, Types, and Examples

Autoimmune Disease

What is an Autoimmune disease? Autoimmune disease occurs when a specific adaptive immune response is mounted against self-antigens. The normal consequence of an adaptive immune response against a foreign antigen is the clearance of the antigen from the body. Virus-infected cells, for example, are destroyed by cytotoxic T cells, whereas soluble antigens are cleared by the formation of immune complexes of antibody and antigen, which are taken up by cells of the mononuclear phagocytic system such as macrophages. When an … Read more

Complement Components and its 7 functional categories

Complement Components

Complement refers to a set of serum proteins that cooperates with both the innate and the adaptive immune systems to eliminate blood and tissue pathogens. Complement components can be classified into seven functional categories: Initiator complement components: These proteins initiate their respective complement cascades by binding to particular soluble or membrane-bound molecules. Once bound to their activating ligand, they undergo conformational alterations resulting in changes in their biological activity. The C1q complex, Mannose-Binding Lectin (MBL) etc. are examples of initiator … Read more

Lymphocytes- Types and Functions

Lymphocytes- Types and Functions

Lymphocytes are the cells that specifically recognize and respond to foreign antigens and are mediators of humoral and cellular immunity. Lymphocytes, the unique cells of adaptive immunity, are the only cells in the body that express clonally distributed antigen receptors, each specific for a different antigenic determinant. Each clone of T and B lymphocytes expresses antigen receptors with a single specificity, which is different from the specificities of the receptors in all other clones. Thus, the antigen receptors of these … Read more

Macrophages- Introductions and Functions

Macrophages- Introductions and Functions

Macrophages The mononuclear phagocytic system consists of monocytes circulating in the blood and macrophages in the tissues. The monocyte is considered a leukocyte in transit through the blood, which becomes a macrophage when fixed in a tissue. Monocytes and macrophages as well as granulocytes are able to ingest particulate matter (microorganisms, cells, inert particles) and are said to have phagocytic functions. The phagocytic activity is greater in macrophages, particularly after activation by soluble mediators released during immune responses, than in … Read more

Apoptosis- definition, pathways, assay, examples (vs Necrosis)


What is Apoptosis? Apoptosis is a normal genetically programmed cell death where an aging cell at the end of its life cycle shrinks and its remaining fragments are phagocytosed without any inflammatory reaction. The term apoptosis was first introduced in a paper in 1972 by Kerr, Wyllie, and Currie to describe a morphologically distinct type of cell death. It consists of a series of biochemical changes that lead to changes in the cell’s morphology or death. It results in the … Read more

Neutrophils – Definition, structure, count, range, functions

Neutrophils - Definition, structure, count, range, functions

Neutrophils Definition Neutrophils are a type of white blood cell with multi-lobed nuclei and stainable cytoplasmic granules. These are the most abundant granulocytes, occupying about 40-60% of the total number of white blood cells in the blood. Neutrophils, like all other blood cells, are formed from the stem cells in the bone marrow. After differentiation in the bone marrow, neutrophils are released into the peripheral blood and circulate for 7 to 10 hours before migrating into the tissues, where they … Read more

Cells of the immune system

Cells of the immune system

The cells that serve specialized roles in innate and adaptive immune responses are phagocytes, dendritic cells, antigen-specific lymphocytes, and various other leukocytes that function to eliminate antigens. Although most of these cells are found in the blood, their responses to microbes usually occur in lymphoid and other tissues. Phagocytes Phagocytes, including neutrophils and macrophages, are cells whose primary function is to ingest and destroy microbes and get rid of damaged tissues. The functional responses of phagocytes in host defense consist … Read more

Precipitation Reaction – definition and applications

Introduction to Precipitation Reaction

Precipitation definition It is a type of antigen-antibody reaction, in which the antigen occurs in a soluble form. When a soluble antigen reacts with its specific antibody, at an optimum temperature and PH in the presence of electrolyte antigen-antibody complex forms insoluble precipitate. This reaction is called a precipitation reaction. A lattice is formed between the antigens and antibodies; in certain cases, it is visible as an insoluble precipitate. Antibodies that aggregate soluble antigens are called precipitins. The interaction of … Read more

Western Blot- Definition, Principle, Steps, Results, Applications

Western Blot

Western Blot Definition Western blot, also known as immunoblotting, is the process of separating proteins and identifying them in a complex biological sample. The use of polyacrylamide gel electrophoresis is a prerequisite for western blotting in order to separate proteins prior to their identification. The process of western blotting involves the transfer of proteins separated by SDS PAGE into an absorbent membrane. The proteins can then be identified on the membrane by different means. Western blotting has revolutionized the field … Read more

Major Histocompatibility Complex (MHC)- Types and Importance

Major Histocompatibility Complex (MHC)- Types and Importance

Major Histocompatibility Complex (MHC) Both T and B cells use surface molecules to recognize antigen, they accomplish this in very different ways. In contrast to antibodies or B-cell receptors, which can recognize an antigen alone, T-cell receptors only recognize pieces of antigen that are positioned on the surface of other cells. These antigen pieces are held within the binding groove of a cell surface protein called the Major histocompatibility complex (MHC) molecule encoded by a cluster of genes collectively called … Read more