CD4 and type 1 diabetes mellitus: Autoreactive CD8+ and CD4+ T lymphocytes, together with B lymphocytes, are important cellular components of the immune infiltrate into the pancreatic islets of Langerhans in Type 1 diabetes (T1D) contributing to the loss of insulin-producing beta (β) cells in the Non-Obese Diabetic (NOD) mouse model of Type 1 diabetes.