Figure 5 Representative histology primary and secondary lymphoid organs of recipient 12 hours after donor specific transfusion. Sections of spleen were examined by immunohistochemistry staining for CFSE label. The section was incubated with HRP conjugated rabbit anti‐FITC antibody and the colour was developed with DAB. Transfused donor CFSE labelled T cells (dark brown) were localised primarily in the white pulp of the spleen (A–C) or non‐follicular areas of the draining lymph nodes (D–F). Comparison H&E stained sections are shown in A and D. WP, white pulp; RP, red pulp; Fo, follicular area.