What is a Leukocyte Adhesion Deficiency?

Leukocyte adhesion deficiency (LAD) is a genetic disorder of the white blood cells, also known as leukocytes. It is an extremely rare condition that weakens the immune system. The white blood cells of a patient who has LAD are typically either unable to make or cannot make enough CD18, a protein that helps the blood to move efficiently to an infection in the body.

Normal-functioning white blood cells or leukocytes will heed a call from the body, sent through the blood vessels, when there is an infection. They will slowly begin to travel to the affected area, in a process known as chemotaxis, so they can help with the healing process. When a patient has leukocyte adhesion deficiency, the white blood cells receive the message, but are unable to move to the site of the infection. This is because they lack the elements that allow them to attach to the walls of the blood vessels and travel efficiently to the wound. As a result, the patient’s infection cannot heal properly.

The two primary types of leukocyte adhesion deficiency are LAD-1 and LAD-2. There is also a third, less defined type known as LAD-3. Also known as the classic type, the LAD-1 type is the most common.

LAD-1 type leukocyte adhesion deficiency can be classified as either moderate or severe. A moderate case involves a steep decline in CD18 protein in the body, which may not cause as severe symptoms, but can still be fatal if not treated effectively. Severe LAD-1 is indicated by very little or no CD18 in the body and requires more urgent care in order to preserve life.

Patients with LAD-2 and LAD-3 types suffer from different kinds of genetic mutations of the leukocytes. Blood cells with LAD-2 have an impaired travel function. In LAD-3, the most recently discovered subtype, leukocytes cannot activate themselves to travel through the blood vessels.

The symptoms of leukocyte adhesion deficiency include constant skin infections, serious internal infections, candidasis, and wounds that are slow to heal. Some patients may also suffer from a severe case of periodontal disease. The disorder is most common among infants and young children.

LAD is usually treated with a bone marrow transplant, which helps to restore normally-functioning white blood cells to the body. Gene therapy may also be used to treat the condition. Antibiotics are also often prescribed in order to help fight the constant infections most patients suffer.