T Helper Cells and the Adaptive Immune System - Essay Example

Other functions of T-helper cells in the body include facilitating the B cell antibody class switching, maximization of bactericidal activity of phagocytes, for example, the macrophages as well as playing an important function in the growth and activation of cytotoxic T cells.

As far as the immunity of the human body is concerned, T-helper cells serve the most important function in adaptive immunity. They play a vital role in nearly all adaptive immune reactions. Apart from helping B cells secrete antibodies and assisting macrophages to destroy microbes that have been ingested, these cells also help in the activation of cytotoxic T Cells to help them kill infected target cells (Rang, H. P. 2003). These cells have a wide range of functions in the body, but they derive their name from the main role they play in the immune system.

They serve an auxiliary function in the immune system by helping other effector cells to perform their functions effectively. Among the cells, they help include cytotoxic T lymphocytes (CTLs) and B cells. The main help they provide to other cells in the immune system includes secreting cytokines which act as stimulators to activate the other cells. There are four main types of T-helper cells namely Th1, Th2, Tfh, and Th17. Each of them performs a specific role in the immune system (Hu, 2007). The Th1 for instance plays essential functions in both antibody-mediated immunity and cell-mediated immunity.

These cells are in the regulation of intracellular pathogens like viruses and certain types of bacteria such as Listeria and Mycobacterium tuberculosis which cause TB (Hu, 2007). Th1 cells provide cytokine-mediated assistance to cytotoxic t Lymphocytes, which are the most powerful cells against intracellular pathogens. Th2 T- helper cells are important in the production of IgE antibodies as well as the production of other subclasses of lgG. They also offer their help to B Cells. The other type of T-helper cell, Tfh also provides help to B cells, assisting them to develop antibodies capable of secreting plasma cells in the nests of lymphoid cells also known as follicles located in the lymph nodes.

These are the majority type of T-helper cells in the body and are commonly known as follicular helper T (Tfh) cells (Hirota et al, 2011). The Th17 T-helper cells on the other hand help in the protection of other body surfaces such as the skin and the lining of intestines from extracellular bacteria. To successfully perform their function, T-helper cells have to be activated to become effector cells. One of the most notable roles these cells play in adaptive immunity is the role it plays in HIV infections.

HIV affects CD4+ cells in the human body. The virus kills all the CD4+ cells reducing their numbers and effectiveness. As a result, the patient’s immunity is inhibited and towards the end of the HIV infection, the patient suffers from Acquired Immunodeficiency Syndrome (AIDS). The absence of CD4+ cells in the body also leads to other rare disorders that produce similar symptoms to AIDS but they are not as fatal as AIDS. During the nonsymptomatic stage of HIV, the virus often has a high attraction toward macrophages and a low one toward the T-Cells (Harrington et al, 2005).

This results in a low skill rate for the CD4+ T cells in the immune system. This situation is initially resolved through the production of other T helper cells from the thymus which originates from the bone marrow. When the virus becomes more lymphotropic and gets attracted to the T cells, it starts to infect the CD$+ T cells more efficiently as a result of a change in the co-receptors that it binds to in the course of the infection. This leads to the immune system being overwhelmed and the body becomes weaker and less resistant to diseases and other infections.