PTPRC and type 1 diabetes mellitus: Finally, considerations of the entire spectrum of islet-associated immune cells permit the definition of an important histopathological correlate for stage 1/2 T1D: the frequency of islets associated with ≥ 1 CD45+ cell constitutes a straightforward metric that readily distinguishes Ctrl (25%) from both AAb and T1DS (45–55%) donors altogether underscoring the significant immune cell recruitment to islets already in the AAb stage (Fig. 5I).