This 10-month-old patient with severe leukocyte adhesion deficiency type I (LAD I) developed a cervical adenitis caused by Klebsiella pneumoniae. Following incision and drainage, wound healing took 4 months.
Leukocyte adhesion deficiency (LAD) is a rare primary immunodeficiency.The clinical picture is characterized by marked leukocytosis and localized bacterial infections that are difficult to detect until they have progressed to an extensive level secondary to lack of leukocyte recruitment at the site of infection. Thus the infections in patients with leukocyte adhesion deficiency act similarly as those observed in patients with neutropenia.
Leukocyte adhesion deficiency type I (LAD I) is a failure to express CD18, which composes the common ß2 subunit of LFA1 family (ß2 integrins). CD11a/CD18 (LFA-1) expressed on lymphocytes is known to play an important role in lymphocyte trafficking (adhesion to vascular endothelium), as well as interactions to antigen presenting cells (APC). LFA-1 also plays a role of cytotoxic killing by T cells. Another member of this family is CD11bCD18 (MacA or CR3) and CD11cCD18(CR4). These 2 members mediate leukocyte adhesions to endothelial cells but they also serve as receptors for iC3b (inactivated C3b). These patients succumb to life-threatening infection, usually within 2 years of life in severe cases of leukocyte adhesion deficiency I (< 1% expression of CD18). In milder forms of leukocyte adhesion deficiency I (1-30% expression of CD8), patients may survive to adulthood.
Leukocyte adhesion deficiency type II is extremely rare; only a handful cases have been reported and most of them are of Middle Eastern decent. It is a defect in the expression of ligands for selectins due to lack of enzymes required for expression of selectin ligands. Patients have leukocytosis, recurrent infections (more prominent in infants and toddlers), and severe growth and mental retardation. This disease is a defect in fucose metabolism (lack of fucosylation of the carbohydrate selectin ligands) that results in failure to express the ligand for E and P selectin, sialyl Lewis-X (CD15s) expressed on leukocytes and endothelial cells. The patients are unable to fucosylate other glycoproteins, including the H blood group polysaccharide.