Tag: immunity and blood groups

A cytotoxic T-cell, also known as Killer T-cells is a T lymphocyte (a type of white blood cell) that kills cancer cells, cells that are infected (particularly with viruses), or cells that are damaged in other ways. When killer T-cells are exposed to antigens, they release the cytotoxins perforin, granzymes, and granulysin. Perforins and granzymes causes pore formation in the antigen which causes the intracellular content of antigen to leak out resulting in cell death.

Memory cells are formed from T-lymphocytes because memory T cells have the ability to recognized specific antigen. They will activate a stronger and faster immune response after they come across the same antigen again

The thymus is a specialized primary lymphoid organ of the immune system. Within the thymus, T cells mature. T cells are critical to the adaptive immune system, where the body adapts specifically to foreign invaders. The thymus is the largest and most active during the neonatal and pre-adolescent periods.  Surgical removal of the thymus results in immunodeficiency because T- cells do not undergo maturation and this results in suppression of the immune system. 

They have a long life which might start from few months and range to their entire life.

Humoral immunity is a type of immunity which is mediated by macromolecules found in extracellular fluids such as secreted antibodies, complement proteins, and certain antimicrobial peptides. Humoral immunity is so named because it involves substances found in the humour or body fluids. It involves B-lymphocytes or plasma cells and is often known as antibody-mediated immunity.

• T-cells are a type of white blood cell that plays a central role in cell-mediated immunity. 
• T-helper cell assists other white blood cells in immunologic processes, including maturation of B cells into plasma cells and memory B cells and activation of cytotoxic T cells and macrophages. These cells are also known as CD4+ T cells because they express the CD4 glycoprotein on their surfaces.
• Cytotoxic T-cells destroy virus-infected cells and tumour cells and are also implicated in transplant rejection. These cells are also known as CD8+ T cells since they express the CD8 glycoprotein at their surfaces.
• So, the correct answer is 'CD 4'.

• The immune system is a host defence system comprising many biological structures and processes within an organism that protects against disease.  The immune system can be classified into subsystems such as the innate immune system and the adaptive immune system, or humoral immunity and cell-mediated immunity. 
  
• Humoral immunity is the aspect of immunity that is mediated by macromolecules found in extracellular fluids such as secreted antibodies, complement proteins, and certain antimicrobial peptides.
  
• Cell-mediated immunity is an immune response that does not involve antibodies, but rather involves the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen.
  

T cell is a type of WBC that plays a central role in cell-mediated immunity. They are called T cells because they mature in the thymus from thymocytes. T cells kill the pathogen by producing - 

• A cytotoxic T cell (also known as TC, cytotoxic T lymphocyte, CTL, T-killer cell, cytolytic T cell, CD8+ T-cell or killer T cell) is a T lymphocyte (a type of white blood cell) that kills cancer cells, cells that are infected (particularly with viruses), or cells that are damaged in other ways..
  
• They have CD - 8 markers on the cell membrane.
•  When cytotoxic T cells recognize (bind to) their target, they produce more FasL at their surface. This binds with the Fas on the surface of the target cell leading to its death by apoptosis. Hence The cells which have CD - 8 markers on the cell membrane are T-cytotoxic cells.
• So, the correct answer is 'T-cytotoxic cells'.