Expression of CD30 on B cells. (A) The histograms show an overlay of CD30 surface expression on B1a (CD5⁺B220^lowCD19⁺), B1b (CD5^lowB220^lowCD19⁺), and B2 cells (B220^highCD19⁺) of the PerC and spleen (n = 3). (B) In silico analysis of immgen.org data showing CD30 (TNFRSF8) mRNA expression in different B-cell populations of the PerC and spleen. (C) The overlays show CD30 and CD86 surface expression of splenic B cells in the absence of stimulation (day 0) and after 1 or 3 days of CD40 plus IgM stimulation. Staining of CD86 was used as positive control for B-cell activation (n = 3). (D) CD30 mRNA expression at different B-cell activation stages after CD40 and lipopolysaccharide (LPS) stimulation of unstimulated follicular B (FoB) cells, CD40/IL4 blasts (B220⁺CD138⁻), CD40/IL4/IL5 plasmablasts (PBs) (B220^lowCD138⁺), LPS blasts (BLIMP1⁻CD138⁻), LPS PB SDC⁻ (Blimp1⁺CD138⁻), LPS PB SDC1⁺ (BLIMP1⁺CD138⁺), and splenic PCs. CD30 mRNA expression was determined by in silico analysis of expression data published by Shi et al.⁴⁹  (E) The histogram shows an overlay of CD30 surface expression of IRF4⁺ vs IRF4⁻ splenic B cells of a control mouse 3 days after immunization with NP-Ficoll. Gating was performed as shown in the dot plot. Dot plots were pregated on a large lymphocyte gate and Thy1.2⁻ cells. The analysis is representative of 2 independent experiments with 3 mice each. FPKM, fragments per kilobase of exon per million reads mapped; MZB, marginal zone B cells.