Egypt J Pediatr Allergy Immunol, (October 2008), Volume No. 6, Issue 02  
Egypt J Pediatr Allergy Immunol 2008 ; 6 ( 02 ) : 69-76 -
, ESP - 75  
Cell-mediated immunity in recent-onset type 1 diabetic children
Wafaa E. Ibrahim   Hala G. Mohamed   Hanan H. Ali   Esmail E. El-Sharnoby      
Background: The ability to suppress an immune response makes regulatory T-cells (T-reg) an attractive candidate as a novel therapeutic agent for treating autoimmune diseases. The mechanisms involved in maintenance of peripheral tolerance include a specialized subset of regulatory-T-cells (Treg) within the T-cell population. The CD4+ CD25+ T-cells may be important in modulating the risk for autoimmunity. Auto-reactive cytotoxic T-cells recognize peptide epitopes displayed on the beta cells surface in the context of HLA class1 molecules. A population of CD8+ regulatory T-cells characterized by expression of CD25 and FOXP3 have been identified and induced in the human peripheral blood cells. The regulatory activity of these cells is on autologous, antigen-reactive CD4+ T-cells in a cell contactdependent manner. These findings provide an evidence for a new mechanism for induction of immune regulation in human. Objective: This study was aiming to assess the cellular immune parameters including the percentage of CD4+, CD8+, CD4+/CD8+ ratio,CD4+CD25+, CD8+ CD25+ lymphocytes, which may have its application in developing immune therapy based tools for halting disease progression. Methods: This study was conducted on 20 children of recent onset type 1 diabetes (disease duration <6 months) who were compared to 10 healthy children. Each child was subjected to determination of CD markers by flow cytometer. Results: The patients group shows a significantly lower CD8+ lymphocyte percentage (p<0.01) and significantly lower CD8+ CD25+ lymphocytes percentage (p<0.05) compared to control group. The CD4+, CD4+/CD8+ ratio, CD4+ CD25+ was not significantly different (p>0.05) between the two groups. A significant inverse correlation was found between CD4+ CD25+ T-cells and HbA1c percentage among patients group (p<0.05).Also a significant difference in the percentage of CD4+ CD25+ T-cells was found when patients with HbA1c<8% were compared to those with HbA1c>8% (the latter group had significantly lower percentage of CD4+ CD8+ T-cells). Conclusion: Type 1diabetes is characterised at its onset by a lowered percentage of CD8+ and CD8+ CD25+ T-cells in peripheral blood, a normal percentage of CD4+ and CD4+ CD25+ T-cells. There may be an inverse correlation between percentage of CD4+ CD25+ T-cells at disease onset and HbA1c level after three months. These data support the hypothesis that a defect in function or deficiency in number of T- regulatory cells may affect the pathogenesis of type 1 diabetes.