Expression of monoclonal antibody HML-1-defined alpha E beta 7 integrin in cutaneous T cell lymphoma.

Considering that integrins may play a major role in the localization in distinct biological features as well as in the dissemination of several types of lymphomas, we studied the expression of the monoclonal antibody HML-1-defined alpha E beta 7 integrin (CD103) in the clinically and histologically determined stages of 53 mycosis fungoides (MF) skin biopsies and in 16 affected lymph nodes. Immunoperoxidase staining revealed HML-1 immunoreactivity with T cells in the early stages of disease (patch and plaque stage MF). HML-1 expression was more pronounced on infiltrating epidermal than on dermal T cells. In contrast to early stages, tumor stage MF and lymph nodes affected in the course of cutaneous T cell lymphoma were HML-1 negative. We found a strong association between HML-1 expression, epidermotropism of infiltrating T cells, and the stage of disease. We provide evidence that: 1) the loss of the HML-1 antigen on T cells in MF is a marker of poor prognosis and 2) because the HML-1 antigen is selectively expressed on T lymphocytes of epithelial sites such as gut and skin, our results are compatible with the view that alpha E beta 7 integrins perform homing receptor functions for epitheliotropic T cells.