Insulitis in type 1 (insulin‐dependent) diabetes mellitus in man—macrophages, lymphocytes, and interferon‐γ containing cells

This study sought to determine, firstly, the relative frequency of lymphocytes and macrophages and, secondly, the percentage of lymphocytes containing interferon‐γ in inflamed islets (insulitis) of patients with type 1 (insulindependent) diabetes. Autopsy pancreases of 12 patients who had died of recent‐onset type 1 diabetes and one prediabetic patient who had died of cardiomyopathy were examined immunohistochemically. In the 87 islets that were studied, the lymphocyte macrophage ratio was 9·7:1 and approximately 40 per cent of the lymphocytes contained interferon‐γ. Interferon‐γ release in the insulitis process may be involved in the pathogensis of type 1 diabetes.