Type-2 diabetes down-regulates glucose transporter proteins and genes of the human blood leukocytes.

OBJECTIVE: White blood cells are essential in mediating immune and inflammatory responses. A prominent feature of these cells during activation of the immune function is increased glucose utilization, and this is dependent on the functioning of specific glucose transporter (GLUT) isoforms. The few data available on leukocyte glucose transporter expression are limited to type-2 diabetes mellitus, and nothing is known about its regulation.
MATERIAL AND METHODS: Peripheral blood was drawn from 35 healthy controls and 35 diabetic subjects. Expression of GLUT1, GLUT3 and GLUT4 was determined in the leukocytes of healthy individuals and diabetic patients by flow cytometry, Western blot and semi-quantitative RT-PCR.
RESULTS: GLUT 3 was decreased in granulocytes, lymphocytes and monocytes from diabetic patients. In monocytes, GLUT3 and GLUT4 were reduced in type-2 diabetic patients. In leukocytes of diabetic patients, GLUT1 and GLUT4, protein and mRNA were unchanged, but GLUT3 protein and mRNA levels were down-regulated compared to those of healthy controls.
CONCLUSION: Elevated glucose concentration affects leukocyte GLUT expression. Decreased expression of GLUT isoforms in leukocytes may be responsible for diminished activation of diabetic leukocytes. These situations possibly contribute to a predisposition to infection and to a decreased immune response in diabetes.