Immunopathogenesis of mycosis fungoides/Sézary syndrome (cutaneous T-cell lymphoma).

T cells are critical effectors of the adaptive immune response and play an important role in cutaneous immunity. In the skin, various cell types cooperate together, from components of both the innate immunity and adaptive immunity, provide sentinel function to mediate the immune response. However, when T cell function becomes abnormal, there is a loss of normal effector immune function, and the abnormal T cells become a cause of disease as well. Mycosis fungoides (MF) is a cutaneous T cell lymphoma (CTCL) that preferentially travels to the epidermis. When skin homing T cells become malignant, the clinical consequences reflect not only the presence of the malignant cells, but likely from a complex reaction of the immune response to the malignant cell. The clinical presentation is the evolving manifestation of the steps in cancer immunosurveillance. Analysis of gene expression in MF/CTCL patients has provided support for the role of the immune response in the early phase of the disease and a loss of immune response in advance stages of MF/CTCL. This review will focus on cytokine gene expression abnormalities in the clinical stages of the disease and discuss the relationship between the clinical and immunologic abnormalities to gain a better understanding of mechanisms important in the evolution of this disease. A better understanding of the immunopathogenesis of MF/CTCL would support innovative strategies for the development of novel therapies to treat this T cell malignancy.