Hepatitis C Tests Cryoglobulins

Hepatitis C- associated Cryoglobulins

Your immune system is always trying to get rid of your hepatitis C infection. Sometimes, this constant stimulation of the immune system can cause trouble. B cells are special lymphocytes that make antibodies - the proteins that can bind to the hepatitis C virus. The hope is that the antibody-bound virus will be taken away by other parts of the immune system. Sometimes, these antibody-virus complexes can build up and then deposit in places where they are not supposed to deposit.

Cryoglobulins (cryo = cold, globulins = proteins) are these antibody complexes that become solid and deposit out, especially in areas of the body where the temperature is lower than 37C, or normal body temperature. It is a bit tricky tryiing to find cryoglobulins - the blood must be processed at body temperature rather than being left out at room temperature. Up to half of the people with hepatitis C have detectable cryoglobulins in blood. Fortunately, only a small minority have symptoms.

The picture on the left is a positive test for cryoglobulins or cryoprecipitate. Most people have no symptoms from cryoglobulins. Some might develop a skin rash when the cryoglobulins deposit in the blood vessels that supply the skin. In medical terms, this is a cutaneous vaculitis. They can initially show up as crops of small red dots that come and go. Over time, these dots become larger and last longer. Eventually, they can become painful ulcers that don't heal.

Cryoglobulins can deposit in other areas including the glomeruli, the part of the kidney that filters blood. This can cause membranoproliferative glomerulo-nephritis (MPGN), a form of kidney damage where you can lose too much protein in the urine (you get a low blood albumin level) and the kidneys can eventually fail. The next picture shows a kidney under the the microscope, with yellow cryoprecipitates in the green staining glomerulus. Other places that can be affected include nerves (some people have reported pain, numbness or weakness when a nerve is affected), and joints. A cancer of the B lymphocytes, lymphoma, can also be associated with chronic hepatitis C infection.