English: The Beta Cells (orange in the lower left cell bundle) are part the insulin-producing cells of the pancreas (the bright highlighted organ in circular picture). In an autoimmune-type attack type 1 Diabetes, the physiologically secreted exosomes (the yellow dots) of the beta cells are wrongly taken up by dendritic cells (big whitish cell with arms) with their contents being presented to T-cells (smaller blue cells in the upper right) . The T-Cells see those contents (proteins) as enemies and attack their producers. This leads to a loss of functional beta cells and a decreased production of insulin.