What Is a Leukocyte Adhesion Deficiency?
Leukocyte adhesion deficiency (LAD) type II (LAD) is a rare primary immunodeficiency disease, and only two cases have been reported so far. LAD is an abnormality of fucose metabolism, which leads to the defect of leukocyte surface selectin ligand fucosylation antigen SLEX, and causes abnormal rolling function of leukocytes, which affects its adhesion to vascular endothelial cells and cannot penetrate the vascular wall into the inflammation area.
Basic Information
- Visiting department
- Division of Rheumatology
- Multiple groups
- Infants
- Common causes
- Fucose metabolism abnormality
- Common symptoms
- Repeated bacterial infections (pneumonia, periodontitis, otitis media, localized soft tissue inflammation, and skin infections), severe mental retardation, special facial features, etc.
Causes of Leukocyte Adhesion Deficiency Type
- The SLEX antigen on the surface of leukocytes serves as a ligand binding site for endothelial cell surface selectin, participates in the adhesion between leukocytes and endothelial cells, and promotes the migration of leukocytes to the area of inflammation. The fucose metabolism is abnormal, and the lack of fucosylated substances, such as the SLEX antigen of selectin ligand, leads to impaired leukocyte adhesion dysfunction, and backward growth and intellectual development.
Leukocyte adhesion deficiency type clinical manifestations
- Recurrent bacterial infections occur shortly after birth and include pneumonia, periodontitis, otitis media, localized soft tissue inflammation, and skin infections. It is characterized by the absence of pus in the infected area. The infection was less severe than LAD, and there was no delay in umbilical cord shedding. Other manifestations include severe mental retardation, short stature, and special features.
Leukocyte adhesion deficiency type test
- Peripheral blood neutrophils are abnormally high. Even in the absence of infection, neutrophils can be as high as (25-30) × 10 9 / L, and as high as 150 × 10 9 / L in acute infection. Neutrophil chemotactic function was significantly reduced, and phagocytosis was normal. Monoclonal antibodies were used to detect the absence of SLEX expression in neutrophils. The half-life of neutrophils in the blood vessels is only 3.2 hours (6-9 hours in normal people), and the metabolic rate is also significantly increased. The number of neutrophils released from the bone marrow into the blood is eight times that of normal people.
- Generally, various auxiliary examinations are selected according to clinical needs, and chest radiographs and B-ultrasounds are often required.
Leukocyte adhesion deficiency type diagnosis
- Repeated infection but no pus formation, with special facial and mental retardation, as well as parents' close marriage history and laboratory tests can confirm the diagnosis.
Leukocyte adhesion deficiency type treatment
- Antibacterial therapy can effectively control bacterial infections, and generally does not require prophylactic use of antibacterial drugs. Chronic periodontitis and severe mental retardation are difficult to resolve. Consider adding fucose to your diet or giving fucose intravenously. Children are often negative for the H-antigen of red blood cells (H-antigen is also a fucosylated antigen). If repeated intravenous infusion of fucose can induce the body to produce antibodies against H-antigen, resulting in severe hemolytic anemia, it should be used with caution .
Leukocyte adhesion deficiency type II prognosis
- Repeated infections to nutritional deficiencies and growth retardation, severe infections can lead to death of children, and severe mental retardation is difficult to resolve.