Definitive

A male or female patient with defective expression of CD18 on leukocytes (less than 5% of normal) and at least one of the following:

1. Mutation in the β₂ integrin gene.
2. Absence of β₂ integrin mRNA in leukocytes

Probable

A male or female patient with defective expression of CD18 on leukocytes (less than 5% of normal) and all of the following:

1. Recurrent or persistent bacterial or fungal infections
2. Leukocytosis (WBC greater than 25,000/mm³)
3. Delayed separation of the umbilical cord and/or defective wound healing

Possible

Infant with marked leukocytosis (WBC greater than 25,000/mm³) and one of the following:

1. Recurrent bacterial infections
2. Severe deep seated infection
3. Absence of pus at sites of infection

Spectrum of disease

Marked leukocytosis and recurrent bacterial infections are the hallmarks of LAD. Staphylococcus, gram negative enteric bacteria and fungal infections are particularly troublesome. Periodontitis is a very common persistent finding. In the severe form, no expression of CD18 is detected on neutrophils and early death occurs without BMT. In the moderate form, a small amount of CD18 is expressed and patients can survive to adulthood. Some patients may have normal CD18 expression with a defective CD18 (β₂ integrin) activity.

Exclusion criteria:

1. Normal CD18 and CD15a expression on neutrophils
2. Normal neutrophil counts
3. Normal neutrophil adhesion

Differential Diagnosis

1. Chronic Granulomatous Disease
2. SLeX deficiency (LAD II)

Further information

• Inflammation: The Leukocyte Adhesion Cascade