Tag: immune system, its cells, mediators and antigens

Leucocytes or the white blood cells are the disease-fighting white blood cells that identify and eliminate pathogens. Hence, they are one of the chief components of the innate immune system. A high white blood cell count is referred to as leucocytosis. The innate leucocytes include phagocytes (macrophages, neutrophils and dendritic cells), mast cells, eosinophils and basophils.

Interleukin 2 (IL-2) is an interleukin, a type of signaling molecule that regulates the activities of white blood cells (leukocytes, often lymphocytes) that are responsible for immunity. Granulocyte-macrophage colony-stimulating factor (GM-CSF), also known as colony-stimulating factor 2 (CSF2), a monomeric glycoprotein secreted by macrophages, T cells, mast cells, NK cells, endothelial cells and fibroblasts that function as a cytokine -  a white blood cell growth factor and stimulate stem cells to produce granulocytes (neutrophils, eosinophils, and basophils) and monocytes. Monocytes exit the circulation and migrate into tissue, whereupon they mature into macrophages and dendritic cells. Thus, it is part of the immune system. Tumor necrosis factor (TNF) is a cell signaling protein (cytokine) involved in systemic inflammation and is one of the cytokines that make up the acute phase reaction. It is produced chiefly by activated macrophages. The primary role of TNF is in the regulation of immune cells. Thus, the correct answer is option D.

• A T cell or T lymphocyte is a type of lymphocyte that plays a central role in cell-mediated immunity. T cells can be distinguished from other lymphocytes, such as B cells and natural killer cells, by the presence of a T-cell receptor on the cell surface. They are called T cells because they mature in the thymus.
  
• B cells, also known as B lymphocytes are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system by secreting antibodies. B-cells bind to an antigen, receive help from a cognate helper T cell and differentiate into a plasma cell that secretes large amounts of antibodies and help in phagocytosis.
  
• Phagocytes are cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells.
  

• The acquired immunity involves two types of cells: B-cells and T-cells.T cells are involved in cell-mediated immunity, whereas B cells are primarily responsible for humoral immunity (relating to antibodies).
• Like all blood cells, B(B lymphocyte)- and T-cells9T-lymphocyte) are produced in the bone marrow. B-cells mature in the bone marrow and  T-cells travel through the bloodstream to the thymus gland and mature in the thymus gland.
• Hence B- and T-cells required for the immune system are produced in Bone marrow.
• So, the correct answer is 'Bone marrow'.

Adenosine deaminase deficiency or ADA deficiency is an autosomal recessive disorder that causes immunodeficiency. Gene therapy is a method to treat this. A functional ADA complementary DNA is inserted to the lymphocytes and then grown in an artificial culture. After the growth ADA cDNA is returned to the patient. 

The major histocompatibility complex (MHC) is a collection of genes coding for MHC molecules found on the surface of all nucleated cells of the body. There are two classes of MHC molecules involved in adaptive immunity, MHC I and MHC II. MHC I molecules are found on all nucleated cells, they present normal self-antigens as well as abnormal or non-self pathogens to the effector T cells involved in cellular immunity. In contrast, MHC II molecules are only found on macrophages, dendritic cells, and B cells; they present abnormal or non-self pathogen antigens for the initial activation of T cells.

There are 2 forms of MHC, namely MHC class I and class II proteins. They play important role in the adaptive immunity. They present peptides on the cell surface for recognition by T cells. Helper T cells are part of adaptive immunity. They recognize and activate B cells to secrete antibodies and macrophages to destroy foreign bodies. They also help activate cytotoxic T cells to kill infected target cells. B cells are part of humoral immune response. They recognize soluble antigens. Antigen-presenting cell (APC) are those cells with detects, engulfs and digests antigen.