NK T cell defect in IMD patients. (a) NK T cells in the peripheral blood were characterized by a three-color flow cytometry assay using mAbs to CD3 and to receptors bearing expressed Vα24 and Vβ11. The triple-positive population (CD3⁺Vα24⁺Vβ11⁺) showed marked reductions in both newly diagnosed (P < 0.0001) and long-term immune-mediated diabetic patients (P < 0.007) compared with controls. Nine multi-autoantibody–positive relatives of the 12 patients studied similarly had significantly reduced numbers of triple-positive cells (P < 0.0001). Whereas the type 2 diabetic patients also had lower levels than controls (P < 0.02), their deficiency was less marked than the IMD patients (P < 0.04). The horizontal lines represent means; n is the number of subjects in each group. (b) Comparisons are shown between NK T cells as defined by staining with CD3, Vα24, and mAb to the Vα24JαQ junction (6B11) to NK T cells defined by staining with CD3⁺Vα24⁺Vα11⁺ mAbs in patient and control groups. No differences were found in the NK T cell numbers as stained by the two different sets of mAbs. (c) A dot plot comparing the measurement of NK T cells using Vα24 and Vβ11 mAbs and Vα24 and the invariant JαQ junction mAb (6B11) in a representative normal control and a newly diagnosed IMD patient are shown. The patient has reduced doubly stained cells (upper-right quadrants) using either sets of mAbs. *P < 0.007, **P < 0.04.