γδ T cells as potential contributors to the progression of parapsoriasis to mycosis fungoides.

It has recently been demonstrated that γδ T lymphocytes play a role in innate immunity to the neoplastic process; however, the significance of this subset of T lymphocytes in the pathophysiology of the most common form of cutaneous T cell lymphomas, mycosis fungoides, has yet to be investigated. In order to identify whether γδ T lymphocytes play a role in the progression of a pre-lymphomatous stage (parapsoriasis) to frank lymphoma (mycosis fungoides), we evaluated their presence in the skin biopsies of patients affected by mycosis fungoides and parapsoriasis. The skin biopsies of ten patients with mycosis fungoides and nine patients with parapsoriasis were analyzed using immunohistochemistry with a panel of different antibodies for T cell-associated markers (CD3, CD4, CD5, CD8 and γδ TCR). The percentage of T cells expressing γδ T cell receptors (TCR) was similar in the biopsies from both groups of skin disorders, ranging from 1 to 5% of the total T cell population. We observed a constant presence of T cells bearing γδ TCR in parapsoriasis and mycosis fungoides that did not differ between the two conditions. This presence is consistent with the role played by this subgroup of T cells of the innate immunity system in the development and maintenance of the two skin disorders. However, the contribution of γδ T cells to the progression of parapsoriasis to mycosis fungoides remains to be elucidated.