Cytokines – These are the small protein molecules involved in Signalling. Interleukins, Interfereons, Lymphokines,chemokines comes under this class.
MHC (Major Histocompatibility Complex) – These are a set of surface proteins on almost all Nucleated cell surfaces and on APCs to recognize the foreign substance.They display the peptide fragments of non-self proteins to the Leukocytes. Hence these are also called Human Leukocyte Antigen.
Cluster of Differentiation – These are transmembrane glycoproteins which serves as the CoReceptors of T-Cell receptors. They bind to the MHC molecules specifically,i.e., MHC-class I binds CD8 adhesion molecules onto Cytotoxic T cells, whereas MHC-class II binds CD4 adhesion molecules onto T- Helper cells.
Complement system – It is a system of plasma proteins that complements(enhances) the ability of antibodies and phagocytes to destroy microbes, damaged cells and promotes inflammation.
Antibody – Also known as Immunoglobulin produced by plasma cells of B-Lymphocytes involved in neutralization of foreign particles like pathogens by Antigen-Antibody Interactions.
Antigen –Also known as Immunogen, a molecule capable of stimulating the immune cells to induce Immune response in host cell. In auto-Immune diseases, Antigen is a part of host itself.
Haptens – Small molecules which can induce immune response only when conjugated with a large carrier protein molecule. Antibodies raised against these molecules.
Epitope – The region on Antigen to which Antibody binds, an Antigenic determinanat recognised by the immune cells like T and B-cells.
Paratope – The region of Antibody to which Antigen binds, that is the part of antibody that binds to the epitope.
Phagocytosis – The process of engulfing foreign particle by the phagocytes is known as Phagocytosis. This is called Cell Eating.
Opsonization – It is aprocess of marking the pathogens for destruction during an Immune response. Opsonins are the molecules which Enhances the Phagocytosis.
How does an Immune reponse produced
Whenever an Antigen enters the host cell, it will bind to the host cell. The infected cell sends signals to the immune cells.
Inflammation is a kind of Immune response. In this, Neutrophils, leaves the blood stream and moves towards the infected tissues by a process called Diapedesis.
The detected antigens will be taken up by Antigen presenting cells, which presents the Antigens to the T-Cytotoxic lymphocytes.
The APCs contains MHC(Major Histocompatibility Complex) I and II which activates Tcytotoxic and T-Helper cells.
Macrophages, dendritic cells present the antigens to the lymphocytes. If the antigen gets killed by Tc cells by cell mediated immunity.
Movement of Antigen towards the Phagocytic cell by the process of Chemotaxis. The antigen attaches to the phagocyte.
By Endocytosis, the antigen slowly gets ingested into the phagocytic cell.
The antigen now can be called as a Phagosome as it is wrapped around by the host cell membrane.
This phagosome get fused with the lysosome of phagocytic cell and forms Phagolysosome.
As the lysosomes contain digestive enzyme secretions, the antigen in phagosome will be digested by the lysosomal secretions.
The residual body with indigested particles will be discharged as the waste material by a process of Exocytosis.