Infectious mononucleosis is a clinical syndrome that can be characterized by a multitude of symptoms. They include malaise, headache, fever, pharyngitis, pharyngeal lymphatic hyperplasia, lymphadenopathy, atypical lymphocytosis, and mild transient hepatitis. This disease occurs most often in adolescents and young adults.
Mononucleosis is one of these diseases that are grouped into a class known as a viral infection; more specifically it is caused by the Ebstein-Barr virus (EBV). EBV is a herpes virus. In vitro, EBV only infects human B-lymphocytes. This viral infection results in lymphocyte proliferation and immunoglobulin secretion. The virus usually remains dormant, but can be activated using certain chemicals or when subjected to certain bodily conditions.
To understand how this virus affects the body, we must first have a brief overview of the body and it’s immune system.
The body’s defense mechanisms can be split into two groups; non-specific and specific defense mechanisms. Non-specific mechanisms basically are the barriers that keep pathogens from penetrating the body. For example the epithelial membranes that cover the body, the strong acidity of the stomach killing pathogens before they have the opportunity to infect the system, these are just a couple, there are many others. Specific mechanisms help the individual acquire the ability to defend against specific pathogens by prior exposure to these pathogens. This is a function of the lymphocytes, which will be discussed later on in depth.
Mononucleosis affects the epithelium of the mouth where it is first introduced to the body, but that is the extent to which it is involved in the nonspecific defense mechanisms. The place where it does the most damage is the B-lymphocyte, which is a key component of specific immunity. To understand better what the infection does to the body we must look at the role of lymphocytes in the body briefly and how they do their work.
B-lymphocytes are the ones that are affected directly upon when the body is subjected to this type of infection. Their role in the body is vital for immunity. They are grouped into five subclasses, depending upon some of the polypeptides in their makeup. The basic role of B-lymphocytes is to secrete antibodies that they have made due to them coming into contact with an antigen. Each B-lymphocyte has two sites where specific antigens can combine, and this binding is what promotes the body’s reaction to the infection. The B-lymphocyte is involved in what is called humoral immunity.
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