During inflammation, leukocytes play a key role in maintaining tissue homeostasis through elimination of pathogens and removal of damaged tissue. Leukocytes migrate to the site of inflammation by crawling over and through the blood vessel wall, into the tissue. Leukocyte adhesion deficiencies (ie, LAD-I, -II, and LAD-I/variant, the latter also known as LAD-III) are caused by defects in the adhesion of leukocytes to the vessel wall, resulting in severe recurrent nonpussing infections and neutrophilia, often preceded by delayed separation of the umbilical cord. Although dependent on the genetic defect, hematopoietic stem cell transplantation is often the only curative treatment.