CD4 and type 1 diabetes mellitus: Autoimmune processes that take place in T1DM development include different population of immune cells: CD4+ T-lymphocytes (naive and effector Th1, Th2, Th17, follicular T-helpers Tfh and regulatory CD4+ Treg) (23, 24), CD8+ T-cells (CD8+ stem T-cells, affected CD8+ T-cells, effector memory T-cells, central memory T-cells, exhausted CD8+ T-cells and regulatory CD8+ Treg) (25, 26), and B-cells (CD20+ B-cells, Breg, etc.)(27).