The Mann–Whitney test was used for unrelated samples. Categorical data were analysed in 2 × 2 MAPK inhibitor contingency tables by Fisher’s exact test. A P value of <0·05 was considered significant. Patients with ATL were mostly men (75%) and aged 52·4 ± 3·72 (27–80) years. The duration of ATL–N lesions to the time of clinical diagnosis was 29 ± 10·01 (3–96) months and that of ATL–O lesions was 15 ± 6·94 (2–60) months. We identified the parasite by immunohistochemistry in 8 (100%) ATL–O and 7 (58%) ATL–N lesions. In addition, considering the results of parasite isolation, imprint and immunohitochemistry, 62% of ATL–O and only 8·3% of ATL–N

were positive for more than one test (data not shown). Controls (n = 20) and patients with ATL were similar in gender and age. All 20 ATL samples presented an inflammatory infiltrate predominated by mononuclear cells and granulomas

(Table 1). Of the 14 cases in which the epithelial layer was present, six showed squamous and pseudoepitheliomatous hyperplasia (two ATL–N and four ATL–O). Twelve patients presented ulceration (nine ATL–N and three ATL–O). Among the 20 control subjects, three presented a discrete and diffuse inflammatory infiltrate in the lamina propria. CD3+, CD4+ and CD8+ cells were identified in the epithelium and lamina propria of all subjects. In the lamina propria, T lymphocytes were also observed inside vessels and juxtaposed with the endothelium, and around glands. In ATL lesions, these cells formed an intense, diffuse and homogeneously distributed infiltrate. In contrast, C–N and C–O showed few, heterogeneously check details distributed cells (Figure 1a,b). The percentage and distribution/mm2 of CD3+, CD8+ and CD4+ cells were significantly different between ATL–N and C–N, and between ATL–O and C–O. In contrast, a similar distribution was found in ATL–N and ATL–O (Tables S1 and S2; Figure 2a–c). The CD4/CD8 ratio was similar in the two types of ATL lesions. A significant difference in this ratio was observed between ATL–N

and C–N (P = 0·011) but not between ATL–O and C–O (Table S2). The distribution of CD22+ B cells was heterogeneous, forming clusters of positive cells amid the inflammatory infiltrate of the lamina propria both in ATL lesions and in control tissue. Significant differences were observed between ATL–N and C–N, and between ATL–O and C–O (Tables S1 and S2). The distribution filipin of CD22+ B cells was similar in the two types of ATL lesions (Table S1; Figure 2d). The results showed similar numbers and spatial distribution of T and B lymphocytes in mucosal ATL lesions. Because other cells also participate in the inflammatory reaction, the number and distribution of macrophages, neutrophils and Langerhans cells were analysed. CD68+ cells (macrophages) were detected in the epithelium and lamina propria of ATL lesions. These cells presented an intense, diffuse and homogeneous distribution and were found close and/or juxtaposed with the endothelium of vessels and glandular ducts.