Pediatric Complement Receptor Deficiency Workup

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


Imaging Studies

No specific radiographic studies are necessary to make a diagnosis.

As previously discussed, imaging studies are useful in diagnosing infections.


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.