Hello Maura
I can explain only in the most simple terms, that an immune complex is formed when the immune system mounts an attack on protein that it recognises as "non- self", usually bacterial and viral infections. The protein that provokes the immune system's very complex defense mechanisms is called the antigen. Antibodies are produced to attack the antigen. An immune complex is what's formed when the antibodies bind to the antigens. The immune complex circulates throughout the body system and somehow or another gets processed out of it when the harmful cells have been killed off. The immune system returns to its normal state and we feel better.
In some infectious diseases the immune complexes fail to disappear and the disease becomes chronic; Lyme disease and malaria are examples.
In autoimmune diseases the immune system is malfunctioning because it gets confused between 'self' and 'non -self' proteins, in other words it starts defending the body from its own cells and produces auto- antibodies, antibodies to 'self'.
So disease activity might be measured by the level of circulating immune complexes, and diagnostically the type of disease might be determined by the type of anti bodies or autoantibodies, as always along with symptoms.
There are the different groups of antibodies( immunoglobulins), IgG, IgE,IgM and so on, but many different ones within those general groups.
Sometimes the immune complexes deposit themselves in organs and start causing damage that might be permanent. One school of thought about autoimmune disease is that the problem is not the production of antibodies of any sort, but the body's failure to dispose of the immune complexes in the usual way.
This is just my understanding of an extremely complex subject, how the immune system works, about which much still remains to be understood even at expert level.
Cheers
Clare
