Lymph nodes are small bean shaped or kidney shaped organs present in the lymphatic system. It is an important part of the body immune system. These are found throughout the body and about 800 lymph nodes are present in human body. The size of lymph node is generally about 1 to 2 cm. They are … Read more
Major Histocompatibility Complex II (MHC II) molecules are protein molecules present on the surface of some immune cells. These are mainly found on professional antigen presenting cells (APCs). The cells include dendritic cells, macrophages and B cells. MHC II molecules are different from MHC I molecules because MHC I is present on almost all nucleated … Read more
Type IV hypersensitivity is also called Delayed-Type Hypersensitivity (DTH). It is a cell mediated hypersensitivity reaction. It is due to T lymphocytes. It is not due to antibody. It is called delayed type because the reaction appears late. Usually it appears after 48 to 72 hours. Sometimes more time also needed. This delay is due … Read more
Major Histocompatibility Complex class I (MHC I) is a cell surface glycoprotein which is found on almost all nucleated cells and platelets. In human it is known as Human Leukocyte Antigen (HLA). The main classical forms are HLA-A, HLA-B and HLA-C. MHC I is heterodimer in structure. It is made up of one heavy alpha … Read more
Type III hypersensitivity is also called immune complex mediated reaction. It is caused by deposition of antigen-antibody complex in tissue. The antibodies involved are mainly IgG and IgM. In this reaction soluble antigen is present in blood. This antigen combines with antibody. So immune complex are formed.The reaction is as follows- Soluble antigen + IgG/IgM … Read more
Type II (Cytotoxic) Hypersensitivity is an antibody mediated hypersensitivity reaction in which IgG or IgM antibodies react with antigen present on the surface of body cell or extracellular matrix. In this reaction, the antibody binds with the normal host cell antigen. Then the immune system identifies this cell as harmful cell. It causes injury of … Read more
Type I hypersensitivity reaction is an immediate hypersensitivity reaction. It is also called anaphylactic hypersensitivity. It is produced against some harmless foreign substances called allergens. The allergens may be pollen, food, drugs, dust and insect venom. These substances enter into the body and the immune system reacts against them. The reaction is very fast and … Read more
Autoimmunity is an abnormal condition in which the body immune system react against its own healthy cells and tissues. It means the immune system cannot properly identify self-antigen and foreign antigen. So, the body’s own tissues are attacked like they are infectious agents. Normally, the immune system has a protective mechanism called self-tolerance. This tolerance … Read more
Rh blood group is a human blood group system. It is one of the most important blood group after ABO blood group. It has great importance in blood transfusion and pregnancy. The Rh blood group is mainly identified by Rh factor. This Rh factor is the D antigen. It is present on the surface of … Read more
Immune response is a protective response of body against harmful foreign agents. It is done by physical barriers, immune cells and chemical signals. It helps to maintain normal health of body. The main function of immune response is to identify and destroy pathogens, foreign toxins and abnormal cells. It also removes damaged cells from body. … Read more
