PMC6948281_01
Representative immunofluorescence images of a pancreatic section stained for leucocyte common antigen CD45 (red), C-peptide (green), glucagon (white), nuclei DAPI (blue), illustrating variable immune infiltration of pancreatic parenchyma and islets. (b) and (d) are high magnification images of islets in (a) and (c) respectively. (b) shows the focal aggregation of CD45+ cells at one pole of the islet typical in early T1D and referred to as peri-insulitis.
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fig1
Tumor free pancreas (Figures 1 and 2) showed relatively normal islets with a pancreatic beta cell fractional area measured in sections stained for C-peptide being 0.57 +- 0.09%. The mean immune infiltrate (illustrated in Figures 1 and 3) was 1.95 +- 0.21 CD45+, 1.47 +- 0.18 CD3+, 1.14 +- 0.14 CD8+, and 0.04 +- 0.00 CD68+ cells/islet section, with 3.4% of islets being negative for insulin (pseudo-atrophic islets, Figure 4(c)). CD45+ and CD3+ cells were frequently detected within exocrine pancreas parenchyma either as scattered single cells or as focal dense infiltrates (Figures 1(c) and 4(a)), and often associated with areas of acinar-to-ductal metaplasia (Figures 4(b) and 3(d), 3(e)).
(a) Representative image of pancreatic section stained with H&E: NP-normal parenchyma, *:fat deposition, # : fibrosis, i :a site of inflammation next to the area of acinar-to-ductal metaplasia (box). (b) Cross-sectional view of CT scan slice of the pancreas showing normal density of the head of the pancreas while the neck, body and tail show low density consistent with fatty replacement acinar tissue. (c) High magnification of the boxed area (in (a)) illustrating acinar to ductal metaplasia (arrow) versus normal acinar tissue (arrow head). (d) Image of the same area in the adjacent section immunostained with anti-cytokeratin (green), Ki67 (red) and C-peptide (white).
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fig2
Tumor free pancreas (Figures 1 and 2) showed relatively normal islets with a pancreatic beta cell fractional area measured in sections stained for C-peptide being 0.57 +- 0.09%. Beta cell replication by Ki67 was not detected but areas of increased cell replication were present in areas of acinar to ductal metaplasia (Figure 2(d)). The exocrine pancreas showed more abnormalities than the endocrine pancreas with regions of chronic pancreatitis characterized by acinar to ductal metaplasia (Figures 2, 4(b) and 4(d), 4(e)), inflammation and fibrosis with areas of exocrine atrophy (Figure 2).
Representative immunofluorescence images of the pancreatic sections stained for macrophage marker CD68 (red), insulin (green), glucagon (white) in panels (a-c), or for T cell markers CD3 and CD8 (red and white respectively) and insulin (green) in panels (d and e); blue -nuclei (DAPI). Macrophages were found in peri-islet area (a-c, arrows) or pancreatic parenchyma (b, arrow head). CD8+CD3+ T cells were frequent throughout the parenchyma (d and e, arrow heads), in the areas of acinar-to-ductal metaplasia (d, e, arrow heads), and in the peri-islet area (d-f, arrows).
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fig3
The mean immune infiltrate (illustrated in Figures 1 and 3) was 1.95 +- 0.21 CD45+, 1.47 +- 0.18 CD3+, 1.14 +- 0.14 CD8+, and 0.04 +- 0.00 CD68+ cells/islet section, with 3.4% of islets being negative for insulin (pseudo-atrophic islets, Figure 4(c)). Macrophages were less frequent in pancreatic parenchyma (Figure 3(b)), but were occasionally detected in the islet periphery (Figures 3(a) and 3(b)) and as a cluster inside islets (Figure 3(c)).
Representative immunofluorescence images of a pancreatic section stained for leucocyte common antigen CD45 (red), insulin (green), glucagon (white), nuclei DAPI (blue). Leucocytes are presented scattered throughout the exocrine pancreas as well as in occasional focal aggregates (a, arrow). Leucocytes are also present in areas of acinar-to-ductal metaplasia illustrated in (b). While most islets in this case had beta cells present, as expected in evolving type 1 diabetes, occasional islets were present with no detectable beta cells (c, arrow) or a few beta cells with minimally insulin immunoreactivity (d, arrow).
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fig4
The mean immune infiltrate (illustrated in Figures 1 and 3) was 1.95 +- 0.21 CD45+, 1.47 +- 0.18 CD3+, 1.14 +- 0.14 CD8+, and 0.04 +- 0.00 CD68+ cells/islet section, with 3.4% of islets being negative for insulin (pseudo-atrophic islets, Figure 4(c)). The exocrine pancreas showed more abnormalities than the endocrine pancreas with regions of chronic pancreatitis characterized by acinar to ductal metaplasia (Figures 2, 4(b) and 4(d), 4(e)), inflammation and fibrosis with areas of exocrine atrophy (Figure 2). CD45+ and CD3+ cells were frequently detected within exocrine pancreas parenchyma either as scattered single cells or as focal dense infiltrates (Figures 1(c) and 4(a)), and often associated with areas of acinar-to-ductal metaplasia (Figures 4(b) and 3(d), 3(e)).