RESUMEN
Aim: The aim of this work was designed to assess the expression of Fas receptors on T and B lymphocytes from patients with type 1 diabetes mellitus at different stages of the disease and to analyse the role of the soluble isoform of Fas and caspase-3 in Fas mediated apoptosis of T and B lymphocytes. Subjects and this study was carried on 21 type 1 diabetic patients divided into two groups: newly diagnosed [ND] and longstanding [LS], and 10 normal subjects as control group. All patients were subjected to thorough history taking, clinical examination, and laboratory investigations [fasting blood glucose and glycated haemoglobin], Immunofluorescence staining and flow cytometry analysis for Fas receptors on T and B -lymphocytes was done. Soluble isoform of Fas [S-Fas] was measured in the plasma by Elisa, and caspase-3 activity was assessed by colorimetric chemical method. Fas receptors: expression on T lymphocytes was significantly decreased among ND diabatic patients than LS and normal controls [P<0.001 and P < 0.049] and the percentage of T cells expressing Fas receptors was significantly increased in ND diabetics versus LS and controls [P = 0.000 and P= 0.000]. The soluble isoform of Fas was significantly increased in ND diabetic patients as compared to LS and control groups [P =0.000 and P< 0.015]. There was a positive correlation [r=0.750, P= 0.000] between Fas receptor expression as mean fluorescence intensity ratio of T cells and that of B cells and a negative correlation with s-Fas [r= 0.750, P= 0.000 and r= -0.540, P=0.004 and r= -0.573, P=0.002, respectively] in diabetic patients. Conclusions: Defective apoptosis of peripheral lymphocytes is well documented and clearly expressed both at the cell membrane Fas receptors and plasma s-Fas levels in ND type 1 diabetic patients. So, it is likely that defective Fas-mediated apoptosis of peripheral lymphocytes may contribute partly to loss of tolerance seen in type 1 diabetes mellitus