Cells Involved In Immune System
Introduction
Immunity (derived from immunitas: Latin for exemption from civic duties and prosecution) means protection from disease and especially infectious disease. Cells and molecules involved in such protection constitute the immune system and the reaction against an introduced foreign agent is known as the immune response. Not all immune responses protect from disease; some foreign agents, such as the allergens found in house dust mite, cat dander or rye grass pollen, cause disease as a consequence of inducing an immune response. Likewise some individuals mount immune responses to their own tissues as if they were foreign agents due to autoimmunity. Thus, the immune response can cause the autoimmune diseases common to man such as multiple sclerosis, diabetes, rheumatoid arthritis or myasthenia gravis. Most individuals do not suffer from autoimmune disease because they have developed tolerance towards their own (self) antigens/tissues.
The immune system stockpiles a huge arsenal of cells, not only lymphocytes but also cell-devouring phagocytes and their relatives. All these cells play accessory roles in immunity like activating lymphocytes, increasing the effectiveness of antigen clearance by phagocytosis, or to secrete various immune-effector molecules. Some immune cells take on all comers, while others are trained on highly specific targets. To work effectively, most immune cells need the cooperation of their comrades. Sometimes immune cells communicate by direct physical contact and sometimes by releasing chemical messengers. The immune system stores just a few of each kind of the different cells needed to recognize millions of possible enemies. When an antigen appears, those few matching cells multiply into a full-scale army. After their job is done, they fade away, leaving sentries behind to watch for future attacks.
Authors: Gautam Kapoor, Vivek Verma and Venkatesh Rengaswamy
For Correspondence: E mail : swami.confocal@gmail.com.
FULL ARTICLE PDF 80 KB
