1.1.3 Acquired Immunity
The acquired immunity system comprises B Cells and T Cells.Together, these cells which provide acquired immunity are known as Lymphocytes.The acquired immunity system further divides into two parts, humoral immunity and Cell Mediated Immunity (CMI).
B Cells
B Cells provide Humoral Immunity.Each B cell secretes a unique antibody, which acts against a particular antigen.An antigen is a chemical feature (a protein) which is unique to any given type of invading organism.When B cells meet an invading organism for which they have the antibody,they do one of two things.
· They may turn into antibody factorie s and start manufacturing as many copies of their antibody as they can.
· They may clone themselves, thus increasing the numbers of antibody factories, which results in an increased immune response to the target organism.
T Cells(https://www.daowen.com)
T Cells provide Cell Mediat ed Immunit y, often referred to as “CMI”.T cells have several functions.They can be:
· Helper T cells, which control other cells, such as B cells or Macrophages, directing them to carry out their task.
· Suppressor T cells, which dampen down the immune response when it is no longer needed.
· Cytotoxic T cells, which destroy host cells that have become infected with the invading organism.
Cytokines
Cytokines are the last element of the immune system which we shall discuss here.Cytokines(meaning “cell movers”) are the messengers of the immune system.The above mentioned elements of the immune system (Complement, Phagocytes, Lymphocytes) do not work separately, but all work together in co-operative fashion.If they are to work effectively, they need a good system for communicating messages.This system is provided by the cytokines.Among the cytokines are the Interleukins, of which there are known to be at least twelve, Gamma-Interferon, Lymphotoxin,and Tumor Necrosis Factor.