Fig 1: Developmental trajectories and subgroup transitions of plasma cells exhibiting varying differentiation pathways in the pancreatic lesions of patients with type 1 autoimmune pancreatitis (AIP). A) UMAP plot displaying the annotation of distinct plasma cell subgroups identified within the dataset. B) Bar graph illustrating the relative proportions of each plasma cell subgroup present. C) Left: Pseudotime analysis revealing the differentiation trajectory among plasma cells, highlighting the progression of cell states. Right: Visualization of IGHG4 expression levels specifically in plasma cells. D) The differentiation direction of plasma cells, as determined by the Vector algorithm, is shown; the blue box indicates the proposed starting point of the differentiation process. E) Pseudotime analysis results for plasma cells, illustrating their developmental progression over time. F) Identification of DEGs and functional modules through pseudotime analysis, along with enriched GO terms (p < 0.01). G) The calculation of putative transcription factors associated with each plasma cell subgroup, derived from analysis utilizing the SENIC algorithm. H–J) Selected GO terms for CALR‐positive plasma cells, IgG4‐positive plasma cells, and PRDM1‐positive plasma cells in the type 1 AIP group compared to those in the normal pancreatic tissue or the post‐PBMC group, as determined by Gene Set Enrichment Analysis (GSEA). K,M) Left: Representative immunofluorescence images depicting CALR‐positive plasma cells and PRDM1‐positive plasma cells within the pancreatic lesions of type 1 AIP patients. Scale bars indicate 50 µm. Right: Quantification of the density of CALR‐positive plasma cells and PRDM1‐positive plasma cells in pancreatic tissues from type 1 AIP patients (n = 5) in comparison to healthy controls (n = 5) (***p < 0.001). Scale bars indicate 50 µm.