Defects in granulocyte function in various chromosome abnormalities (Down's-, Edwards'-, Cri-du-chat syndrome)

Area of Science:

• Immunology
• Genetics
• Pediatrics

Background:

• Infants with autosomal aberrations often exhibit recurrent infections.
• Humoral and cellular immune mechanisms may appear intact despite susceptibility to infections.

Purpose of the Study:

• To evaluate granulocyte functions in infants with autosomal aberrations and recurrent infections.
• To identify specific immune defects contributing to diminished resistance to infection.

Main Methods:

• Assessed granulocyte functions including chemotaxis, phagocytosis, intracellular killing, and metabolism.
• Tested phagocytosis of Candida albicans and killing of Staphylococcus aureus and Escherichia coli.
• Measured serum opsonin levels (IgG, IgM, CH50, C3).

Main Results:

• Serum-dependent or cell-dependent phagocytosis defects of Candida albicans were observed in infants with cat-cry syndrome and trisomy 18.
• One infant showed additional serum-dependent defects in killing Candida albicans and Staphylococcus aureus.
• An infant with trisomy 21 exhibited chemotaxis defects and reduced cellular killing of Staphylococcus aureus and Escherichia coli.

Conclusions:

• Specific granulocyte functional defects can occur in infants with autosomal aberrations, contributing to recurrent infections.
• These defects may manifest as impaired phagocytosis or intracellular killing, even with normal opsonin levels.
• Identifying these immune dysfunctions is crucial for understanding infection susceptibility in these infants.