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Immunodeficiency among children with recurrent invasive pneumococcal disease
Helene Ingels1, Lone Schejbel, A C Lundstedt
1From the *Department of Microbiological Surveillance and Research, National Neisseria and Streptococcus Reference Center, Statens Serum Institut, Copenhagen, Denmark; †Department of Paediatrics and Adolescent Medicine, ‡Department of Clinical Immunology, Copenhagen University Hospital, Rigshospitalet, Denmark; §Department Clinical Biochemistry, Immunology, and Genetics, Statens Serum Institut, Copenhagen, Denmark; and ¶Department of Clinical Microbiology, Slagelse Hospital, Slagelse, Denmark.
Insights
Recurrent invasive pneumococcal disease (IPD) in children can be linked to undiagnosed immunodeficiencies, particularly complement C2 deficiency. Screening for complement deficiencies and poor antibody response is recommended for children with recurrent IPD.
Area of Science:
- Pediatric Infectious Diseases
- Immunology
- Genetics
Background:
- Recurrent invasive pneumococcal disease (rIPD) in children often lacks an identifiable cause.
- Immunodeficiency is suspected in some rIPD cases, but its prevalence is not well-established.
- A nationwide registry of laboratory-confirmed rIPD cases was utilized to investigate unexplained occurrences.
Purpose of the Study:
- To identify unexplained cases of rIPD in children.
- To screen these children for various forms of immunodeficiency.
- To determine the prevalence of specific immunodeficiencies in unexplained rIPD.
Main Methods:
- Children aged 0-15 with rIPD from 1980-2008 were identified.
- Unexplained cases underwent screening for complement function, T-cell, B-cell, and NK-cell counts, and immunoglobulin levels.
- B-cell function was assessed via antibody response to pneumococcal vaccination and somatic hypermutation extent; Toll-Like Receptor (TLR) signaling was also examined.
Main Results:
- Out of 2192 IPD cases, 68 were rIPD in 54 children; 15 unexplained cases were analyzed.
- Complement C2 deficiency was found in 6 children (40%) of the analyzed group.
- Impaired vaccination response occurred in 6 children, with 3 also being C2 deficient; one had severe TLR signaling dysfunction.
Conclusions:
- At least 11% of an unselected cohort of children with rIPD exhibited C2 deficiency.
- The findings support screening for complement deficiencies in children with recurrent IPD.
- Evaluating antibody response to pneumococcal vaccines is also suggested for these patients.
Background:
Recurrent invasive pneumococcal disease (rIPD) occurs mostly in children with an underlying disease, but some cases remain unexplained. Immunodeficiency has been described in children with rIPD, but the prevalence is unknown. We used a nationwide registry of all laboratory-confirmed cases of rIPD to identify cases of unexplained rIPD and examine them for immunodeficiency.
Methods:
Cases of rIPD in children 0-15 years of age from 1980 to 2008 were identified. Children without an obvious underlying disease were screened for complement function, T-cell, B-cell, natural killer--cell counts and concentration of immunoglobulins. B-cell function was evaluated by measuring antibody response to polysaccharide-based pneumococcal vaccination and the extent of fraction of somatic hypermutation. Toll-Like receptor (TLR) signaling function and mutations in key TLR-signaling molecules were examined.
Results:
In total, rIPD were observed in 54 children (68 cases of rIPD of 2192 IPD cases). Children with classical risk factors for IPD were excluded, and among the remaining 22 children, 15 were eligible for analysis. Of these 6 (40%) were complement C2-deficient. Impaired vaccination response was found in 6 children of whom 3 were C2 deficient. One patient had a severe TLR signaling dysfunction. No mutations in IRAK4, IKBKG or MYD88 were found.
Conclusion:
Of an unselected cohort of children with rIPD at least 11% were C2 deficient. Data suggest that screening for complement deficiencies and deficient antibody response to pneumococcal vaccines in patients with more than 1 episode of IPD is warranted.
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