Lymphoid disease of Eμ:TCL1 mice without or with enforced B-cell–specific BCL2 expression. Heterozygous Eμ:TCL1; CD19^Cre (TC) controls and Eμ:TCL1; CD19^Cre; BCL2 (TCB) animals were compared. (A) The time course of the percentages of total and CLL-like B cells in the peripheral blood of TC and TCB mice was measured by flow cytometric quantification of Cd19⁺ leukocytes. (B) Spleen weights of wild type (WT) (n = 10), TC (n = 23), and TCB (n = 7) mice at an age of 30 weeks. (C) In cohorts of TC (n = 68) and TCB (n = 34) mice the median overall survival was 50 or 41 weeks, respectively (P = .0028). (D) Immunohistochemistry of exemplarily 1 representative TC vs 4 TCB spleens in hematoxylin and eosin (HE), CD3, and CD19 staining reveals follicular structure in TC and TCB mice at 30 weeks. (E) Lysates were generated from B cells from TC (n = 5) and TCB (n = 4) mice and splenocytes from 1 WT B6 mouse at the age of 28 to 30 weeks. Immunoblots were generated for the BCL2, antiactin, TCL1, and Glyceraldehyd-3-phosphate-dehydrogenase (GAPDH). Coomassie stainings are provided for both membranes as controls of protein quality and loading. TCL1 protein level is higher in TC mice (∗P = 0259); whereas BCL2 protein level is higher in TCB mice. (F) Splenocytes of 30-week-old TC (n = 11) and TCB (n = 5) mice were analyzed by flow cytometry and the relative amounts of different B-cell developmental stages were quantified. Debris and doublets were excluded from singlets. Viable cells were defined via FS INT/SS INT. GFP⁺ population was gated/CD19⁺ population was gated. (G) Debris and doublets were excluded from singlets. Viable cells were defined via forward scatter intensity/ side scatter intensity (FS INT/SS INT). Green fluorescent protein (GFP⁺) population was gated. The total B-cell population (GFP⁺) was gated in the IgM vs IgD plot defining the subpopulations. (H) Debris and doublets were excluded from singlets. Viable cells were defined via FS INT/SS INT. GFP⁺ population was gated defining the B cells. Defining the GFP⁺/CD93^– population out of viable cells. The total GFP⁺/CD93^– population was gated in the CD23/CD21/35 plot. Follicular cells are defined as CD93^–/CD23⁺/CD21/35⁺ B cells (GFP⁺). (I) Debris and doublets were excluded from singlets. Viable cells were defined via FS INT/SS INT. GFP⁺ population was gated defining the B cells. The total GFP⁺ population was gated in the Cd95 vs GL7 plot. Germinal center cells are defined as CD95⁺/GL7⁺ B cells (GFP⁺). (J) Debris and doublets were excluded from singlets. Viable cells were defined via FS INT/SS INT. The total viable population was gated in the GFP vs CD5 plot defining the subpopulations. (K) Debris and doublets were excluded from singlets. Viable cells were defined via FS INT/SS INT. CD3⁺ population was gated defining the T cells. The total CD3⁺ population was gated in the CD4 vs CD8 plot defining the CD4⁺ and CD8⁺ subpopulation of the CD3⁺ T cells. (L) Clonal percentages of IgH isotypes were determined by Ig sequencing of splenic B lymphocytes from individual animals. (M) Bulk RNA sequencing of splenic B cells was performed and evaluated as previously described for diffuse large B-cell lymphoma (DLBCL) models, using the same reference gene sets.⁸ The enrichment of upregulated regulated activated B-cell (AB^up) and germinal center (GC^up) gene sets defined by 3´ RNA sequencing from WT animals was determined by comparing the transcriptional profiles of TCB and TC lymphoma. ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; and ∗∗∗∗P < .0001. Welch unpaired 2-tailed t test performed for panels A,B,E,F,G,H,I,J,K; log-rank test performed for panel C.