Pediatric Complement Receptor Deficiency Workup

Updated: Dec 19, 2016
  • Author: Alan P Knutsen, MD; Chief Editor: Harumi Jyonouchi, MD  more...
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Workup

Laboratory Studies

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  • Extreme neutrophilia (>15,000/mcL) is a constant feature of leukocyte adhesion deficiency (LAD) type 1, type 2, type 3, and Rac2 deficiency because of inability of neutrophil margination.
    • The WBC count is 15-161 X 103/µL (15,000-161,000/mcL) with 50-90% neutrophils.
    • Neutrophilia is present in the absence of infections and increases with infections.
    • In E-selectin deficiency, mild neutropenia is present but increases with infections.
  • The diagnosis of LAD type 1 is confirmed by an absence of CD11a,b,c/CD18 on neutrophils, macrophages, and lymphocytes on flow cytometry.
    • In addition, neutrophil function is impaired, with abnormal adherence, chemotaxis phagocytosis, and deficient respiratory burst.
    • Numbers of T and B cells and their function are normal.
    • However, natural killer (NK)-cell and T-cell cytotoxicity is depressed.
    • Responses on mixed lymphocyte culture (MLC) may be markedly decreased.
    • CD15s expression is normal in LAD type 1.
  • In LAD type 2, CD15s (sLeX) expression is absent on neutrophils. CD11/CD18 expression is normal.
    • Neutrophil rolling is decreased but adhesion is normal.
    • Numbers and function of T and B cells are decreased.
    • Erythrocyte H antigens are absent, leading to expression of the Bombay (hh) phenotype. As a result, anti-H antibodies are present.
  • In examination of infections in children with LAD type 1, signs of inflammation, eg, erythema, pus formation, are decreased to absent.
    • Necrotic cutaneous, mucous membrane, and periodontal infections are the hallmark of LAD type 1.
    • In deep-seated infections, such as in the lungs and abdomen, the same process occurs.
    • Inflammatory infiltrations are decreased.
    • Therefore, findings on chest or abdominal radiography findings may lead to underestimates of the infectious process.
    • Imaging studies more sensitive than radiography, such as chest CT, may define the infectious process better than radiography.
    • Appropriate cultures are obtained from suspected infectious sites. Although inflammatory cells are decreased to absent, microorganisms can be identified.
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Imaging Studies

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  • No specific radiographic studies are necessary to make a diagnosis.
  • As previously discussed, imaging studies are useful in diagnosing infections.
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Histologic Findings

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  • The most striking finding in biopsies of infections in patients with all forms of LAD is the absence of neutrophils and other inflammatory cells.
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