Photopheresis is a leukapheresis-based
therapy that utilizes
8-methoxypsoralen and ultraviolet A irradiation.
Photopheresis is currently available at approximately 150 medical centers worldwide. Recent evidence suggests that this
therapy used as a single agent may significantly prolong life, as well as induce a 50%-75% response rate among individuals with advanced
cutaneous T cell lymphoma (CTCL). Furthermore, a 20%-25% complete response rate with
photopheresis alone, or in combination with other
biologic response modifiers, has been obtained at our institution among patients with
Sezary syndrome. These complete responses have been characterized by the complete disappearance of morphologically atypical cells from the skin and blood. The use of sensitive molecular techniques has also confirmed the sustained disappearance of the malignant T cell clone from the blood of patients with complete responses. In addition to the treatment of CTCL, numerous reports indicate that
photopheresis is a potent agent in the
therapy of acute allograft rejection among cardiac, lung, and renal transplant recipients.
Chronic graft versus host disease also appears to be quite responsive to
photopheresis therapy. Likewise, there may also be a potential role for
photopheresis in the
therapy of certain
autoimmune diseases that are poorly responsive to conventional
therapy. The immunologic basis for the responses of patients with these conditions is likely due to the induction of anticlonotypic immunity directed against pathogenic clones of T lymphocytes. Treatment-induced apoptotic death of pathogenic T cells and activation of antigen presenting cells are postulated to have important effects in this therapeutic process.