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Primary leucocyte alkaline phosphatase deficiency in an adult with repeated infections

Insights

A primary deficiency in leucocyte alkaline phosphatase (LAP) was identified in a patient with recurrent bacterial infections and eczema. This deficiency marginally impaired neutrophil bactericidal activity, particularly against high bacterial loads.

Area of Science:

  • Immunology
  • Biochemistry
  • Cell Biology

Background:

  • Primary immunodeficiencies can manifest with recurrent infections and specific enzyme deficiencies.
  • Leucocyte alkaline phosphatase (LAP) plays a role in neutrophil function.
  • Hyperimmunoglobulin E syndrome is associated with immune dysregulation and eczema.

Observation:

  • A patient presented with recurrent bacterial infections, eczema, and elevated immunoglobulin E levels.
  • This individual exhibited a primary deficiency of leucocyte alkaline phosphatase (LAP).
  • Neutrophils from the patient showed normal leucotaxis, metabolism, and morphology.

Findings:

  • Neutrophil bactericidal activity was marginally deficient in the LAP-deficient patient.
  • Impaired bacterial killing was most pronounced at high bacteria-to-neutrophil ratios.
  • This case contrasts with other described primary or secondary LAP deficiencies.

Implications:

  • Highlights a specific role for LAP in neutrophil-mediated bacterial clearance.
  • Contributes to understanding the heterogeneity of immune defects in primary immunodeficiencies.
  • Suggests LAP deficiency as a potential factor in recurrent infections despite normal neutrophil morphology and metabolism.

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