Cell-mediated immunity in recent-onset type 1 diabetic children

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 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 HbA1c8% (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. Keywords: Type 1 diabetes, cell-mediated immunity, children Egypt J Pediatr Allergy Immunol 2008; 6(2): 69-76