Fig. 1

Immunohistochemistry results of tonsil and NLPHL. a PD-1 (red) and b CD57 (green) fluorescent staining of tonsil. Shown is exactly the same area of a germinal center (×400) with different filters. Arrows indicate some of the PD-1+ cells which are CD57−. c Percentage of PD-1+ cells in the CD57+ T-cell population in tonsil and NLPHL; 94 and 92 % of the CD57+ cells express PD-1 in tonsil and NLPHL, respectively. d Percentage of CD57+ cells in the PD-1+ population in tonsil; an average of 48 % of PD-1+ cells are CD57+. e Percentage of CD57+ cells in PD-1+ population in NLPHL, an average of 39 % of PD-1+ cells are CD57+. f PD-1(red) and CD57 (green) staining of NLPHL (×800). The nucleus is counter stained with DAPI (blue). In the center an LP cell surrounded by PD-1+ cells, three of which are also positive for CD57 (green yellow) is shown. g Percentage of CD57+ cells in PD-1+ rosetting cells in NLPHL, the range of PD-1+ LP rosetting cells that are CD57+ varies from 0 to 58 %. h CD57 (dark red rim), BCL-6 (brown nucleus), CD20 (blue) staining in tonsil (×400). CD57+ cells are also BCL-6+. Some of the CD20+ cells also express BCL-6. Part of the cells are single positive for BCL-6. i CD57 (dark red rim), BCL-6 (brown nucleus), CD20 (blue) staining in NLPHL: (×600). An LP cell (CD20+ and BCL-6+) is surrounded with two types of cells: BCL-6 and CD57 double positive cells and BCL-6 single positive cells