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CD4 and CD25 cells in children under the age of 5 diagnosed with type І diabetes mellitus

Background and aim Type І diabetes mellitus (T1DM) is a T-cell-mediated, chronic disease characterized by a deficiency or absence of insulin, when the body’s own immune system attacks the β cells in the islets of Langerhans of the pancreas. The increased incidence of T1DM in children under the age of 5 years and the aggressive process of β-cell destruction in this age group indicate the need to assess the immune system. CD4+CD25+high regulatory T cells (Tregs) appear to be critical in regulating immune responses to self-antigens. The aim of this study is to evaluate CD4+CD25+ Tregs frequency in the peripheral blood of children diagnosed with T1DM under the age of 5 in comparison with those diagnosed at a later age and healthy controls. Patients and methods The present study was carried out on 80 children who were classified into three groups: group I included 20 children with newly diagnosed T1DM under the age of 5; group II included 20 children with newly diagnosed T1DM older than 5 years of age; group III included 40 apparently healthy children as a reference group divided into age-dependent groups. The history of all children included in the study was recorded. Clinical examination and laboratory investigations included fasting and postprandial serum glucose, renal and liver function tests, complete blood count, glycated hemoglobin, and fasting C-peptide. Flow cytometric analysis was carried out for peripheral blood lymphocytes using monoclonal antibodies against CD4 [fluorescein isothiocyanate (FITC) labeled] and CD25 [phycoerythrin (PE) labeled]. Results We found that both patient groups had highly significantly lower mean percentage of CD4+CD25+high Tregs in comparison with the control groups. Also, a highly significantly lower mean% CD4+CD25+high Tregs in patients younger than 5 years of age in comparison with patients older than 5 years of age was found. Also, diabetic children younger than 5 years of age had a highly significantly lower fasting C-peptide than diabetic children older than 5 years of age. Conclusion This study highlights the distinctiveness of diabetes in children under age of five who had a low secretion of C-peptide which reflect a more destructive lesion of β-cells with consequent lower absolute cell mass in this age group and very low CD4+CD25high T-regs that evince the pathogenesis of autoimmunity. Understanding the differences in the immune system activity in young diabetic children may pave the way toward identification of children at risk of T1DM and enable the use of novel forms of intervention.