Leukocyte Adhesion Deficiency (LAD)
LAD is an immune deficiency in which phagocytes are unable to move to the site of an infection to fight off invading germs. This inability to fight germs results in recurrent, life-threatening infections and poor wound healing. LAD is an autosomal recessive disease, meaning two copies of the abnormal gene are present.
LAD is caused by the absence of a molecule called CD18. These molecules are normally found on the outer surface of phagocytes. Without them, phagocytes cannot attach to blood vessel walls and enter infected tissues, where they help fight infection. ITGB2 is the gene that instructs, or codes for, the production of CD18, and mutations in this gene cause LAD.
Signs and Symptoms
Children with LAD cannot fight off infection and may have any of the following:
- Severe infections of the soft tissue, including skin, muscles, ligaments, and tendons
- Eroding skin sores without pus
- Severe infections of the gums with tooth loss
- Infections of the digestive system
- Wounds that heal slowly or not at all
The severe form of LAD, known as type 1, may cause death in infancy or early childhood. Children with a more moderate form of the disease may survive into young adulthood.
Blood tests can diagnose children with LAD, who have a very high number of white blood cells and very low levels of CD18. A doctor may suspect LAD if wounds do not heal properly. Children who develop severe infections caused by bacteria and whose wounds are slow to heal also may have LAD.
Treatment and Research
Doctors prescribe antibiotics to prevent and treat infections. Some children with LAD have been treated successfully with bone marrow transplants, which replaces defective immune cells with those of a healthy donor.
NIH researchers continue to study LAD in order to develop new therapies and better understand the role of CD18 in the immune system. Recent research suggests that over-production of an immune signal called IL-17 may contribute to the severe oral infections observed in people with LAD. While targeting IL-17 may be a promising therapy, more research is needed.