Detection of Insulitis by Pancreatic Scintigraphy With ^sup 99m^Tc-Labeled IL-2 and MRI in Patients With LADA (Action LADA 10)

Pancreatic scintigraphy with interleukin-2 radiolabeled with 99mTc (99mTc-IL-2) is a technique used to image chronic inflammatory-mediated disorders. We used this method to detect a signal consistent with the presence of insulitis in patients with autoimmune diabetes. Positive and negative controls (patients with pancreatic carcinoma and type 2 diabetes, respectively) also were studied. We examined 25 patients with autoimmune diabetes (16 with recently diagnosed type 1 diabetes, 9 with latent autoimmune diabetes in adults [LADA]), 6 with type 2 diabetes, and 7 with pancreatic carcinoma (the latter two groups were used as negative and positive controls, respectively). All patients underwent 99mTc-IL-2 scintigraphy and contrast-enhanced MRI of the pancreas. To validate positive controls, samples were taken from patients with pancreatic carcinoma during surgery for histological and immunohistochemical investigations. Pancreatic accumulation of 99mTc-IL-2 was detected in patients with autoimmune diabetes (61% positive) and, notably, in 6 of 9 patients with LADA; semiquantitative evaluation of pancreatic uptake of 99mTc-IL-2 showed higher values in patients with autoimmune diabetes (both childhood and LADA) and pancreatic carcinoma than in those with type 2 diabetes (4.45 ± 1.99, 4.79 ± 1.1, and 4.54 ± 1.62 vs. 2.81 ± 0.63; P = 0.06, P = 0.01, and P = 0.04, respectively). In patients with pancreatic carcinoma, pancreatic interleukin-2 receptor expression correlated with pancreatic 99mTc-IL-2 uptake (r = 0.8; P = 0.01). In patients with LADA, 99mTc-IL-2 uptake inversely correlated with duration of disease (r = 0.7; P = 0.03). Autoimmune diabetes in adults is associated with increased pancreatic 99mTc-IL-2 uptake, indicating the presence of insulitis, particularly within 1 year of the beginning of insulin therapy, similar to type 1 diabetes at diagnosis.