Density of neoplastic lymphoid infiltrate, CD8+ T cells, and CD1a+ dendritic cells in mycosis fungoides.

BACKGROUND/AIMS: CD8+ T cells and epidermal/dermal dendritic cells expressing CD1a are found among neoplastic CD4+ T cells in mycosis fungoides (MF) lesions. This study analysed the relation of CD8+ tumour infiltrating lymphocytes (TILs), CD1a+ epidermal Langerhan's cells (LCs), and dermal dendritic cells (DDCs) to clinicopathological parameters in 46 MF cases.

METHODS

Pretreatment diagnostic biopsy specimens of 46 MF cases were submitted to histological analysis and immunohistochemistry. Four histological grades were defined based on the density of the neoplastic infiltrate: grade 1 (mild superficial perivascular infiltrate), grade 2 (moderate superficial perivascular infiltrate with some tendency to confluence), grade 3 (pronounced superficial band-like infiltrate), and grade 4 (deep nodular infiltrate). Epidermotropism was scored as low, moderate, or high. Numbers of CD8+ T cells and of dermal and epidermal CD1a+ cells were scored as 1 (low), 2 (moderate), and 3 (high). Correlations between these parameters and clinical data (age, sex, clinical type of lesions, stage, response to treatment, and recurrence) were analysed by the chi(2) test.

RESULTS

Numbers of TILs and DDCs were associated with subepidermal infiltrates, being lower in less dense infiltrates, whereas there was no association between epidermal CD1a+ cells and the analysed parameters. Complete remission in treated patients was related to subepidermal infiltrates but not to TILs, LCs, or DDCs.

CONCLUSIONS

These results support the notion that CD8+ cells and dermal CD1a+ cells are active against tumour cells. MF with low numbers of TILs could represent an early stage of the disease, before TILs are activated against tumour specific antigens.