I'm also in the forty something generation, although I sometimes feel eighty! Know what you mean about the tiredness - my doc has recommended provigil but my insurance won't pay for it.
Antibodies are one of those confusing issues it's almost impossible to explain in plain English, but let me try. As you probably know, Antibodies are substances produced by the body's immune system in response to bacteria, viruses, or other foreign substances. They are also called immunoglobulins (Ig). Antibodies attach to the foreign substances, causing them to be destroyed by other immune system cells. Usually, antibodies are specific to each type of foreign substance. Sometimes the immune system starts to produce antibodies against a person's own tissues - this is called auto-immunity. Diseases like lupus are characterized by an autoimmune response to the body's own tissues and organs, so they are called autoimmune disorders.
There are five major types of antibodies - IgA, IgG, IgM, IgD, and IgE. IgG antibodies are found in all body fluids. They are the smallest but most common of the antibodies, making up about 75% to 80% of all the antibodies in the body. IgG antibodies are considered the most important antibodies for fighting bacterial and viral infections. They are also the only type of antibody that can cross the placenta during pregnancy.
Chromatin is a complex of DNA and protein found inside the nuclei of certain cells. So antibodies to chromatin are sometimes called anti-nucleosome antibodies.
Anti-chromatin antibodies are considered specific for lupus because, unlike ANA (antinuclear antibodies), they rarely occur in people with no underlying disease. They do occur in some people with scleroderma or other autoimmune disease, but are more likely to occur in lupus. They can also-occur in drug-induced lupus.
So what IcG antichromatin means is that your body is producing the IcG type of antibody to the chromatin in some of your cells. About 50-70 percent of lupus patients will test positive for these antibodies. There is a correlation between antichromatin antibodies and kidney involvement in lupus, so people with these antibodies need to have their kidney function checked regularly.
I hope this explains a little. If you are having trouble finding information on the internet, try searching for anti-nucleosome antibodies instead.