The relationship between MZB counts and SLE clinical parameters and a proposed model of defective B cell development in SLE. (A) Scatter plots of flow cytometry data demonstrating no difference in MZB frequency in African Caribbean (-AC) and Caucasian (-C) HCD and SLE patients (medians, Mann–Whitney test). (B) Correlation of MZB and SLE disease activity index (SLEDAI) score in Caucasian SLE patients (Spearman’s rank coefficient). (C) Bar graphs demonstrating the immunosuppressive burden of SLE patients with low MZB counts (<3.13% CD19⁺ cells) versus high MZB counts (>3.13% CD19⁺ cells), where 3.13% represents the median MZB value in all SLE patients. MMF, mycophenolate mofetil; HCQ, hydroxychloroquine; PRED, prednisolone. (D) Scatter plots of flow cytometry data demonstrate that PV patients taking mycophenolate mofetil and/or prednisolone did not have reduced MZB when compared with SLE patients on the same immunosuppressive medication (mean ± SD, unpaired t test). (E) Scatter plots of flow cytometry data demonstrate there was no difference in MZB counts in nonrenal SLE (OL) patients taking or not taking hydroxychloroquine (HCQ) therapy (medians, Mann–Whitney test). (F) Proposed model of MZB differentiation and alterations seen in severe SLE.