Immunology and AllergyTier 2Disease (DEADMAN)

Neutrophil abnormalities - leucocyte adhesion deficiency

Description

Leucocyte adhesion deficiency (LAD) - a rare primary immunodeficiency from defective neutrophil adhesion molecules, preventing neutrophils from leaving the bloodstream to reach sites of infection

Epidemiology

Rare, autosomal recessive; LAD type 1 (the most common subtype) results from CD18 (beta-2 integrin) deficiency

Aetiopathogenesis

Neutrophils cannot firmly adhere to endothelium (integrin-mediated step of the adhesion cascade) -> cannot transmigrate into infected tissue despite normal or markedly elevated circulating neutrophil counts (neutrophilia, since they cannot leave the blood to be consumed at infection sites)

Diagnosis

Recurrent bacterial and fungal infections without pus formation (since pus requires neutrophil accumulation in tissue) is the classic clinical clue
Delayed umbilical cord separation (beyond ~3-4 weeks) is a characteristic early sign in infancy
Markedly raised neutrophil count with recurrent infection and absent pus should prompt flow cytometry for CD18 expression

Management

Aggressive treatment of infections given the impaired local response; haematopoietic stem cell transplant is curative and considered for severe LAD-1

Associations

Recurrent skin/mucosal infections, poor wound healing, periodontal disease

Natural history & complications

Severe LAD-1 (near-absent CD18 expression) carries high mortality in infancy without transplant; milder/partial deficiency has a more indolent course

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