Increased T lymphocytes bearing the gamma-delta T cell receptor in subjects at high risk for insulin dependent diabetes

The effector mechanisms responsible for autoimmune β cell destruction in insulin dependent (type 1) diabetes (IDD) remain elusive. In order to investigate whether T lymphocytes bearing the gamma-delta T cell receptor (γδ⁺ T cells) could be involved in this process, we measured percentages of peripheral blood γδ⁺ T cells in IDD patients, relatives of IDD probands and controls. High levels of γδ⁺ T cells strongly differentiated 23 relatives at high risk for IDD on the basis of positive islet cell autoantibodies (ICA positive relatives) from 59 controls (P = 0.0013), whereas 26 ICA negative relatives, 14 recent-onset and nine long term IDD patients could not be distinguished from controls on the basis of percentages of γδ⁺ T cells. These data suggest that increased levels of circulating γδ⁺ T cells correlate with the ongoing autoimmune process in pancreatic islets of subjects at high risk for IDD and may thus represent an additional marker for the development of the disease.