Immunoglobulins are proteins called globulins, specifically immunoglobulins (Ig) or antibodies (Abs). They are made by B-lymphocytes and appear on the outside of cells when seen under a microscope. The antibodies that these cells produce are in response to the presence of foreign substances called antigens.
B-lymphocytes make five different types of antibodies: IgA, IgG, IgM, IgE, and IgD. The type of antibody produced is based on the type of antigen detected and the method of stimulation. IgE, for example, is the response of choice for allergic reactions.
For the most common antigens, (flu, viruses, and the like) the first antibody made is usually IgM. How the antigen got into the patient's system also plays a role. IgA is usually made if the antigen was found in body fluids such as saliva while IgM usually responds to GI tract antigens. IgG is the first responder for blood borne items and the final choice for more antibodies.
Eventually, the antibody destroys the antigen, and a small number of cells settle into a memory state. They are no longer making the antibody, but the next time they recognize that specific antigen, they will react faster and more efficiently. This "memory" cell is the cell responsible for the protection we have from vaccinations.
Normal levels of immunoglobulins vary somewhat, but are typically as follows:
When responding to antigens, these levels will rise.
CLL patients--particularly those with progressive disease--may not be capable of producing sufficient quantities of immunoglobulins in which case their ability to fight infections may be diminished. In these cases, patients are sometimes given immunoglobulins intravenously to help them fight infections.