Figure 1.

Ectopic lymphoid structures in progressive MS are characterized by infiltration of lymphocytes, FDCs and plasma cells. (A) Parenchyma of FFPE sections of brain and spinal cord of progressive MS patients were screened for infiltrated regions by H&E staining. (B) IF staining for CD3⁺ T cells and CD20⁺ B cells on serial sections were used to determine the infiltration score. Score 0, no or <5 lymphocytes; score 1, at least five but <30 lymphocytes; score 2, 31 to 60 lymphocytes; score 3, more than 60 lymphocytes. (C) Meninges and sulci of FFPE sections of brain and spinal cord of progressive MS patients were screened for infiltrated regions by H&E staining. (D) IF staining for CD3⁺ T cells and CD20⁺ B cells on serial sections were used to determine the infiltration score. Score 0, no or <5 lymphocytes; score 1, at least five, but <30 lymphocytes; score 2, 31 to 60 lymphocytes; score 3, more than 60 lymphocytes. (E) Whole slides were screened for infiltration on H&E, representative infiltration area depicted in the box (F), and serial sections were stained, depicted in the box (G–O). eLFs are characterized by (G) CD3⁺ T cells and CD20⁺ B cells, (H) CD4⁺ T cells and CD138⁺ plasma cells, (I) CD3⁺ T and CD3⁺CD4⁺ T helper cells (J) Ki67⁺ proliferating cells, (K) CD35⁺ and, (L) CD21⁺ FDCs, (M) CD68⁺ macrophages as well as (N) BCL-6⁺ and (O) CXCR5⁺ GC-like lymphocytes. (P) CD3⁺CD8⁺ cytotoxic T cells as well as some CD3⁺CD27⁺ memory T cells were also present in eLFs. Scale bars (A–D), (F) indicate 100 μm; (E) indicates 2,000 μm; (G–P) indicate 50 μm.