Fig. 2
Characterization of B1 progenitors in the neonate peritoneal cavity. a The neonatal cells were highlighted in the initial UMAP projection, and they were re-projected into nine clusters (C1-C9) based on Harmony corrected latent space. b Distribution of gene expression in UMAP plots. The color key indicates the expression level. c Neonate peritoneal CD19+CD20−IL-7Rα+CD93+ B cell progenitors were analyzed by flow cytometry. Neonates (day 5, pool of 7 pups from 1 litter) were used. d The dynamic change of the proportion of CD19+CD20−IL-7Rα+ CD93+ B cell progenitors during the first few weeks after birth (n = 3 per time point). The error bars indicate the s.e.m. *P < 0.05. e FACS plots showing expression of MHCII molecules and CD138 in CD19+CD20−IL-7Rα+CD93+ B cell progenitors. Neonates (day 5–6, n = 3) and young adult mice (week 8–12, n = 3) were used in the analysis. f Projection of the B1 cell progenitor signature (B1 cell progenitor signature was from a previous study [15], see more details in Methods). The color key indicates the average log normalized expression of the B1 signature genes over the randomly sampled reference genes. g The FACS plots showing the adoptive transfer results. 2–4 weeks after injection of indicated cells directly into the peritoneal cavity of Rag2−/− recipient mice (n = 3 for each donor cell type), peritoneal cells of recipient mice were isolated and analyzed by flow cytometry. Neonates (day 5–6, pool of 25 pups from 3 litters) and young adult mice (week 8–12, n = 2) were used as donors. h Heat map of the expression levels of the indicated genes in C1, C2, C3, and C4 cells. The color key indicates the expression level. i Volcano plot showing the differentially expressed genes (DEGs) between C1 and C2 cells. DEGs (FDR < 0.01) were plotted. j Volcano plot showing the differentially expressed genes (DEGs) between C3 and C4 cells. DEGs (FDR < 0.01) were plotted. k FACS plots showing the expression of Bcl11a in neonate peritoneal Lin−CD19−C-kitlowSca-1low cells. Neonates (day 6, pool of 12 pups from 2 litters, n = 3) were used. The error bars indicate the s.e.m. **p < 0.01. l FACS plots showing the adoptive transfer results. 2–4 weeks after intravenous injection of indicated cells into Rag2−/− recipient mice (n = 3 for each donor cell type), peritoneal cells of recipient mice were isolated and analyzed by flow cytometry. Neonates (day 6, pool of 26 pups from 3 litters) and young adult mice (week 8–12, n = 2) were used as donors. Data are representative of three (c, d, g, k, l) independent experiments