[The immune system and its relation with infection process in children]

Area of Science:

• Pediatric Immunology
• Infectious Diseases
• Immunodeficiency

Background:

• Infections like pneumonia and sepsis pose significant risks to children.
• Understanding immune system deficiencies is crucial for predicting infection outcomes.
• Distinct types of immunodeficiency may correlate with specific infection types.

Purpose of the Study:

• To investigate the relationship between specific immunodeficiencies and the type of severe infection (pneumonia vs. sepsis) in children.
• To characterize the immunological profiles associated with fatal pneumonia and sepsis in pediatric cases.

Main Methods:

• Studied the immune systems of 30 children with pneumonia and 56 with sepsis.
• Assessed humoral immunity (B-cell function, antibody production) and cellular/phagocytic immunity.
• Examined thymus and lymphoid organ development in relation to immune status.

Main Results:

• Children with humoral immunodeficiency (77%) predominantly died from pneumonia.
• Humoral deficiency involved thymus fatty transformation, underdeveloped B-zones, and low IgM, lacking IgG/IgA.
• Children with cellular/phagocytic deficiency (41%) more often died from sepsis, showing thymus immaturity/dysplasia.

Conclusions:

• Humoral immunodeficiency is strongly linked to fatal pneumonia, often presenting with respiratory lesions.
• Cellular and phagocytic immunodeficiency is associated with fatal sepsis, characterized by necrotic changes.
• These findings underscore the importance of identifying specific immune defects for targeted treatment and prognosis in pediatric infections.