Fig. 2: Eosinophils, neutrophils, and mast cells are prominent in type 1 diabetes donors.

Granulocytes from the nPOD data are distinguished based on secretory granule morphology. a Eosinophils were found in exocrine tissue of one donor. b Neutrophils are detected in multiple type 1 diabetes, predominantly located in the exocrine parenchyma and some in the peri-islet region, as shown here. Mast cells are observed in type 1 diabetes (c) and control samples (e). Tryptase+ mast cells are identified by prominent scrolls in the secretory granules (d), and chymase-tryptase+ mast cells show homogenous gray granules (f). Total numbers and prevalence of the innate immune cells per dataset are displayed in Table 1. g Mast cells present per 10⁵ μm² in the total dataset per donor, each symbol represents one donor. Average numbers of total mast cells did not significantly differ between control (1.4 ± 0.60), autoantibody-positive (2.4 ± 0.57; p = 0.068 versus control), and type 1 diabetes donors (2.3 ± 0.49; p = 0.062 versus control). However, tryptase+ mast cells were found significantly higher in autoantibody-positive donors (AAb+; mean = 1.7 ± 0.55, p = 0.02; n = 17) and type 1 diabetes donors (T1D; mean is 2.2 ± 0.50, p = 0.005; n = 24) than control non-diabetes donors (ND; 0.81 ± 0.57; n = 21). Means from tryptase+ mast cell numbers are indicated by horizontal lines. Statistical analyses between control, autoantibody positive, and type 1 diabetes donor groups were performed first by non-parametric one-way ANOVA resulting in tryptase+ mast cells (p = 0.014), followed by Mann–Whitney U tests. (*) Significant differences. n Indicates number of individual datasets analyzed per condition. Bars: 5 μm (a–c, e) 0.5 μm (d, f). Donors 6064 (a), 6380 (b), 6087 (c, d), and 6126 (e, f).