Figure 4.

Immunohistochemistry of patient lymph node (LN) and spleen samples. Representative images of immunoperoxidase stainings of LN (A) and spleen (B) tissues. Large germinal centers were identified by staining for BCL6 in the patient’s LN and compared to LN of a healthy control (control). Additional GC markers, such as IgG defining immunoglobulin class-switched plasmablasts, Ki67 for labeling centroblasts, ICOS and PD-1 for follicular T-helper cells (T_FH cells), IRF-4 marking plasma blasts, and BLIMP-1 for GC B cells poised to develop into plasma cell are shown in (A). Additional staining of IgD (resting follicular B cells), IgM (follicular and marginal zone B cells), CD20 (B cells), CD4 (T-helper cells), Ki67 (proliferating cells), ICOS and PD-1 (T_FH cells), PD-L1 (B cells and DCs), and CD25 (activated T cells and T_REG cells) in the spleen are shown in (B). Mature plasma cells were identified by staining for CD138 in (A). Scale bars; black, 500 µm; white, 100 µm; gray, 50 µm.