Diffuse Lymph-Nodes Microangiopathy as Concurrent Cause of Immunodeficiency in Long-Term Insulin-Dependent Diabetic Patients

Immune abnormalities have been demonstrated in vitro models in genetic (type1) autoimmune (type 2) and metabolic (type 1 and type 2) Insulin-Dependent Diabetes Mellitus (IDDM). However, the precise reason for increased susceptibility to frequent and protracted infections in diabetic patients is still unclear, despite a multitude of in vitro studies which have focused on the metabolic and functional modifications of immune cells Diabetes microangiopathy, which is a peculiar alteration of the disease, has been extensively described in the retina, renal glomeruli, skin, skeletal muscles, peripheral nerves, and other organs but not in lymph nodes. We report our histological and immunohistochemical observations in lymph-nodes removed in multiple sites during autopsy from four patients with long-term IDDM, severe lymphocytpenia and several infectious diseases during their life. The peculiar microangiopathic modifications made by presence of hyaline substance thickening basal membrane of thin vessels and capillaries appear concurrent with lymphodepletion of B and T cells dependent areas of lymph-nodes and with jointed marked reduction of Follicular Dendritic Reticulum Cells (FDRC). Indeed microangiopathy further compromise the traffic and diapedesis of T and B lymphocytes may prevent the transformation of endothelial cells into FDRC with severe immune failure of lymphoid follicles. The histological and immunohistochemical data in this study could provide additional insights into the complex problem of the immunodeficiency in diabetic patients.