Fig 2: Circulating Myeloid Cells Expressing FcRn are Elevated in PDAC Patients. PBMCs of non-cancer (n = 8) and PDAC (n = 13) patients were permeabilized and stained for FcRn. Representative t-SNE plots of the (A) most prevalent cell populations; and (B) FcRn localization from two individual non-cancer and four individual PDAC patients are shown. (C) Quantification of FcRn expression within each immune population. Granulocytes are denoted as Gran, and monocytes are denoted as Mono. Biological replicates represent staining and analyses of each individual sample. Individual biological replicates were combined into box and whisker plots representing the median and interquartile range (25–75%) with whiskers representing the outlying 25%. All statistical comparisons are unpaired t-tests with a Welch’s correction.

Fig 3: FcRn Positivity and Expression are Altered in Murine Splenocyte Immune Populations. Splenocytes from five different tumor-free (TF) or pancreatic tumor-bearing (PDX-1-Cre, LSLKrasG12D, LSL-Trp53−/−) mice were permeabilized and stained with either anti-FcRn or an isotype control antibody. Biological replicates represent staining and analyses from five different animals per group. (A) Representative histograms of FcRn and isotype control are provided for TF and pancreatic tumor-bearing mice with isotype peaks in gray and FcRn peaks in black. Each cell type was assessed for FcRn positivity and the mean fluorescence intensity (MFI). Quantification of splenocyte FcRn positivity and mean fluorescence intensity (MFI) for (B) migratory cDC2 (CD8−CD11b+CD103+CD24++); (C) mMDSC (CD11b+Ly6G−Ly6C+); (D) gMDSC (CD11b+Ly6G+Ly6C+/−); (E) cDC2 (CD8−CD11b+CD103+CD24++), (F) Langerhans DCs (MHC class II+CD11b+CD11c+Ly6C−DC-sign+; (G) moDCs (MHC class II+CD11b+CD11c+/−Ly6C+DC-sign+); (H) pDC (CD11b−CD11c+Ly6C+CD317+); (I) cDC1 (CD8+CD11b−CD103−CD24+); and (J) macrophages (CD11b+CD64+F4/80+). Per sample FcRn positivity is measured by dividing the cells that express FcRn by the total cells within each population. Per sample normalized MFI is calculated by dividing the geometric mean of the FcRn channel for each sample by its isotype control. Biological replicates represent staining and analyses from five different animals per group. All samples analyzed were from a single experiment with five biological replicates per group. Individual biological replicates were combined into box and whisker plots representing the median and interquartile range (25–75%) with whiskers representing the outlying 25%. All statistical comparisons are unpaired t-tests with a Welch’s correction.

Fig 4: Myeloid FcRn Cellular Expression is Elevated in PDAC Patients. Per-cell expression of FcRn quantified by analyzing the mean metal intensity (MMI; non-cancer, n = 8; PDAC, n = 13) (A) All MMI values were normalized and provided in a representative heatmap for each individual sample. In addition to immune populations from Figure 3A, subsets of T cells, monocytes, dendritic cells and MDSCs are presented. Quantified MMI plots of non-cancer (n = 8, black) and PDAC (n = 13, red) (B) T cells, (C) B cells, (D) granulocytes, (E) dendritic cells (F) monocytes, (G) MDSCs, and (H) NK cells. Box and whisker plots represent the median and interquartile range (25–75%) with whiskers representing the outlying 25%. All statistical comparisons are unpaired t-tests with a Welch’s correction.