Analysis of peri-islet CD45-positive leucocytic infiltrates in long-standing type 1 diabetic patients

Aims/hypothesis The role of peri-islet CD45-positive leucocytes, as one component of insulitis, in beta cell death during human type 1 diabetes remains unclear. We undertook a case study, comparing and quantifying leucocytes in the peri- and intra-islet areas in insulin-positive and -negative islets, to assess whether peri-islet leucocytes are pathogenic to beta cells during type 1 diabetes. Methods Pancreatic sections from 12 diabetic patients (0.25–12 years of disease) and 13 non-diabetic individuals with and without autoantibodies were triple-immunostained for islet leucocytes, insulin and glucagon cells. Islets were graded for insulitis, enumerated and mapped for the spatial distribution of leucocytes in peri- and intra-islet areas in relation to insulin- and glucagon-immunopositive cells. Results In the non-diabetic autoantibody-negative group, the percentage of islets with insulitis was either absent or