Increased proportions and altered anatomical localization of CD57⁺ T cells in FL. (A) Proportions of CD57^BRIGHT CD4⁺ T cells in the indicated tissue are expressed as the percentage of the total CD4⁺ T cells. Triangles represent values for individual samples, and rectangles represent averages for each tissue type expressed as a percentage of the total CD4⁺ T cells. *P < .05, **P < .01, and ***P < .001 compared with FL. (B) ICH analysis of CD57⁺ cells within RLNs and FL. In RLNs, CD57⁺ cells are highly restricted to the GC and show polarization, with a relative abundance in the LZ (Bi-iii). This stereotypic distribution was seen in 10 of 10 RLN specimens, even when the node showed other features of inflammation such as necrotizing granulomata (* in Biii). In contrast, the distribution of CD57⁺ cells varied widely among FL specimens. Random microscope fields were selected (original magnification, ×100) from 20 cases of FL, and the location of 200 CD57⁺ cells was noted as either follicular or otherwise. Three of 20 cases had more than three-quarters of the CD57⁺ cells within follicles (Bvi), 11 of 20 showed more than three-quarters of CD57⁺ cells outside follicles (Bv, in which the CD57⁺ cells appear associated with a mantle zone), and 6 of 20 showed a mixed distribution of cells (Biv). (C) IHC analysis of CD57 and CD4 shows CD57⁺ cells colocalized to areas of CD4⁺ cells in a FL nodal section.