ABSTRACT
Diabetes is a chronic disease associated with selective destruction of the pancreatic B-cells. The exact etiology of the disease is unclear; however, insulin deficiency results from autoimmune destruction of B-cells. The appearance of auto antibodies to beta cell antigen, such as those against the 65-KDA isoform of glutamic acid decarboxylase GAD65 and the protein tyrosine phosphates in the peripheral circulation is a predictive sign of clinical disease in non diabetic individuals. Although GAD65 and IA-2 [insulin auto antibodies] may not be directly involved in the pathogenic processes in beta-cell destruction. They are good markers in assessing the risk of disease manifestation. This study aimed to evaluate GAD65 [glutamic acid decarboxylase] and ICA [islet cell auto antibodies] and IA-2 [insulin auto antibodies] auto antibodies as a disease markers and their relationship to certain residual beta cell function and glycemic control in type I diabetes and risk group, and assess the relation between CD4 [+] CD25 [+] [T-regulatory cells] and immune mediated diabetes. This study was conducted on 50 subjects randomly selected from those attending pediatrics outpatients clinics in the period of 2008. The subjects were classified into 3 groups: 1-Group A [patient group]: This group included 20 patients diagnosed as type I DM according to WHO classifications. Their ages ranging from 3-16 years with a mean age of 10.6 +/- 4.0. They were 11 males and 9 females. 2-Group B: [Risk group]: included 20 sibling of diabetic [type I DM] father, mother or both. They were 9 females and 11 males their ages ranging from 18 years to 25 years with a mean of age 21 +/- 2.5. 3-Group C: Control group, included 10 healthy children; they were 5 females and 5 males, their ages ranging from 5-16 years with a mean age of 10.8 +/- 2.8, with no family history of diabetes mellitus. All subjects are subjected to: Complete history taking, Full clinical examination, Complete blood picture, Glycosylated Hb using ion-exchane chromatography, C-peptide of insulin by-ELISA, determination of GAD 65, ICA and IA-2 auto antibodies by ELISA technique, Flowcytometric measurement of the expression of the CD4 [+] /CD25 [+] of T-regulatory cell. The most frequently encountered antibody in children group was GAD65 in 60% of cases, followed by ICA, 40%. When taken together, both GAD65 and ICA were detected in 30%. IA-2 was detectable only in 30% of cases. When both GAD65 and IA-2 were taken together, they were detected in 25% of cases also ICA and IA-2 were detected in 15% of cases. When GAD, ICA and IA-2 were taken together, they were detectable in 5% of cases. The most frequently encountered antibody in risk group was ICA in 15% of cases, followed by GAD, in 10%. When taken together, both GAD65 and ICA were detected in 10%. IA-2 was detectable only in 10% of cases. When both GAD65 and IA-2 were taken together. they were detected in 5% of cases also ICA and IA-2 were detected in 15% of cases. When GAD, ICA and IA-2 were taken together, they were detectable in 5% of cases. There was highly significant difference between 3 groups for prevalence of GAD65 autoantibody [p<0.001] and significant difference between 3 groups for prevalence of ICA autoantibody [p<0.005] and significant difference between 3 groups for prevalence of IA-2 autoantibody [p<0.003]. There were highly significant differences in the level of fasting C-peptide of insulin between patient and control groups. [p value<0.001]. There were significant difference between level of fasting Cpeptide and single and multiple autoantibody positivity [p<0.05]. In the children group the mean and SD of the percentage of CD4 [+] CD25 [+] from CD4 cells were 0.96, 0.46 respectively. In the control group the mean and SD of the percentage of CD4 [+] CD25 [+] from CD4 cells were 2.85, 0.92 respectively. The difference between control and study group according to the mean and SD of the percentage of CD4 [+] CD25 [+] from CD4 cells was statistically highly significant [p<0.001]. In the Risk group the mean and SD of the percentage of CD4 [+] CD25 [+] from CD4 cells were 0.99, 0.7 respectively. In the control group the mean and SD of the percentage of CD4 [+] CD25 [+] from CD4 cells were 2.96, 0.62 respectively. The difference between control and risk group according to the mean and SD of the percentage of CD4 [+] CD25 [+] from CD4 cells was statistically non significant. There was highly sig relation [p<0.001] between percent of CD4 [+] CD25 [+] out of CD4 cells and the presence and absence of auto antibodies in the children group. There was no sig relation between percent of CD4 [+] CD25 [+] out of CD4 cells and the presence and absence of auto antibodies in the in risk group. At the time of diagnosis almost all patients with type I diabetes have auto antibodies that are reactive to islet antigens and auto antibodies GAD, ICA, lA-2 are of' value for predicting IDDM in sibling of diabetic parents type I also CD4[+] CD25[+]T-regulatory cells actively suppress activation of the immune system and prevent pathological self-reactivity