Figure 3

Classical and non-classical tertiary lymphoid structures. The pictures show representative immunohistochemical stainings on consecutive sections of two different oral squamous cell carcinoma (OSCC) tissue samples (A/C vs. B/D) for detection of classical (A/C) and non-classical (B/D) tertiary lymphoid structures (TLSs). B-cell follicles of classical TLSs normally comprise contiguous meshworks of CD21+ follicular dendritic cells (FDCs), as indicated in (A), and show distinct accumulations of germinal centre (GC) B-cells when staining a consecutive section for BCL6, as presented in (C). B-cell follicles of non-classical TLSs usually contain scattered FDCs, as shown in (B; arrows), and lack GC B-cells on a consecutive section stained for BCL6 (D). In some cases, non-classical TLSs also show abnormal GCs with BCL6+ cells dispersed throughout the follicle (data not shown). CD21+ and BCL6+ cells are stained brown, and cell nuclei are stained blue by hematoxylin. Scale bars indicate 40 μm.