Delineating the immunological profile of Algerian children with Down syndrome: A case series.

PURPOSE: This study aimed to characterize the immunological profile of Algerian children with Down Syndrome (DS).

METHODS

Serum immunoglobulin (Ig) levels were measured using nephelometry, and lymphocyte subpopulations were analyzed by flow cytometry (FACSLyric™, BD Biosciences, US). The lymphocyte phenotype in DS patients was compared to that of patients with combined immunodeficiency (CID).

RESULTS

Our cohort included 33 patients with DS (20 males), and 40 patients with CID (24 males). All patients had a clinical history of recurrent or severe infections, including upper and lower respiratory tract infections in 25 patients (76%). Serum Ig were measured in 29 patients, with normal levels of IgG, IgA, and IgM in 83%, 73%, and 80% of patients, respectively. Elevated IgG, IgA, and IgM levels were found in 14%, 17%, and 3% of patients, while reduced levels were seen in 3%, 10%, and 17% of patients, respectively. Lymphocyte phenotype analysis revealed CD4 lymphopenia in 24 (73%) patients, CD8 lymphopenia in 19 (58%) patients, B-cell lymphopenia in 16 (48%) patients, and reduced NK cells in 7 (21%) patients. Naïve CD4+ and CD8+ T cells were analyzed in nine patients, with low percentages observed in three. Patients with DS exhibited significantly milder CD3 and CD4 lymphopenia compared to those with CID.

CONCLUSION

Children with DS typically present with T- and B-cell lymphopenia, while maintaining generally normal Ig levels. T-cell lymphopenia in DS is less pronounced than in CID, and the increased susceptibility to infections stems from both immunological and non-immunological factors linked to trisomy 21.