Fig 2: Cathepsin B-deficient mice have abnormal follicle architecture.a Analysis of lymph node presence and morphology from WT and Ctsb-/- lymph nodes. b Percentage of B cells, CD4+ and CD8+ T cells in WT and Ctsb-deficient LNs determined using flow cytometry, with significance assessed using a Student’s t test. c Staining of WT and Ctsb-/- LNs with anti-B220 (B cells), anti-Podoplanin (Stroma), anti-CD4 (T cells) and anti-CD21/35 (follicular dendritic cells). d Staining of WT and Ctsb-/- LNs for CD19 (B cells) and Meca-79 (PNAd+ HEVs). e Entry of CFSE transferred WT B cells into the LN parenchyma of either WT or Ctsb-/- recipient mice was assessed by confocal microscopy. f Ratio of LN entry of KO:WT B cells into either WT or Ctsb-/- recipients. To determine the relative efficiency of WT vs Ctsb-/- B cells to enter into WT or Ctsb-/- recipients, equal numbers of CSFE (ThermoFisher)-labeled KO cells and CMTMR (ThermoFisher)-labeled WT cells were transferred into corresponding recipient mice. The ratio of transferred B (B220+) cells KO:WT was calculated by taking into account the relative efficiency of CFSE and CMTMR labeled survival post transfer by calculating the ratio of WT CSFE:WT CMTMR transferred cells. g Quantification of migrated CSFE-positive B cells by flow cytometry. h Analysis of Cxcl13 and Cxcr5 mRNA expression from total LN from WT and Ctsb-deficient mice using RT-qPCR. For panels (f-h), significance was assessed using a Student’s t test with p values provided for each comparison. Source data are provided as a Source Data file.

Fig 3: Grossly normal surface phenotype of B1a and MZ B cells in WT, IgM-/- and IgD-/- mice.(A) Plots show CD19+ PerC cells gated to identify CD5+ B1a cells (reduced in IgM-/- as shown in Figure 4—figure supplement 1). Histograms depict CD5 and CD19 expression in B1a cells. (B) Plots show B220+ splenocytes gated to identify CD21hiCD23lo MZ B cells. Histograms depict CD21 and CD23 expression in MZ B cells.

Fig 4: B cell lymphopenia in the absence of TIA1 and TIAL1(A) FACS analysis of CD19+ B cells in LNs from Tia1 cKO (Tia1fl/flTial1fl/+Mb1Cre), Tial1 cKO (Tia1fl/+Tial1fl/flMb1Cre), double Tia1 Tial1 cKO (Tia1fl/flTial1fl/flMb1Cre) mice and Rag2-/- mice.(B) Gating strategy for B cell analysis in spleen.(C) Proportion of total CD19+ B cells, follicular (FO) (CD19+ CD93– CD21+ CD23+), marginal zone (MZ) (CD19+ CD93– CD21hi CD23–), and transitional (T1, CD19+ CD93+ IgMhi CD23–; T2, CD19+ CD93+ IgMhi CD23+; T3, CD19+ CD93+ IgM+ CD23+) B cells in Tia1 cKO, Tial1 cKO, and double Tia1 Tial1 cKO mice.(D) Number of B cells in the spleen of mice shown in (C).Data in (A)–(D) are from two independent experiments performed with at least three mice/genotype. In (C) and (D), each point represents an individual mouse. Mann-Whitney tests in (C) and (D). See also Figure S1.