Pediatric Complement Receptor Deficiency Workup

Updated: Aug 06, 2019
  • Author: Alan P Knutsen, MD; Chief Editor: Harumi Jyonouchi, MD  more...
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Workup

Laboratory Studies

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

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

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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