Background: In patients with Sezary syndrome undergoing extracorporeal photochemotherapy it is currently thought that photodamage of a congruent number of pathogenic circulating T cells is a necessary condition for a specific anticlonal response to be induced against these cells by the immune system. However other mechanisms of action, such as the induction of release by photoirradiated monocytes of some cytokines, are thought to cooperate in the induction of a therapeutic response.
Objective: We investigated the effects of extracorporeal photochemotherapy on peripheral blood mononuclear cells in seven stage Ib cutaneous T cell lymphoma patients.
Method: Samples of peripheral blood were taken before starting extracorporeal photochemotherapy (baseline), and before the 3rd and 6th cycle of treatment, and then incubated with specific monoclonal antibodies.
Results: The results showed a significant increase of CD8+ and CD36+ and a significant decrease of CD25+ in all the treated patients.
Conclusion: Our results show that extracorporeal photochemotherapy is able to induce an increase of CD36+ cell in peripheral blood of patients with mycosis fungoides in its early stages. This subset of monocytes could be involved in the complex mechanism of action of extracorporeal photochemotherapy.