[Clinical and flow cytometry outcome of improved photopheresis methods in dermatologic patients]

In photopheresis, 8-methoxypsoralen (8-MOP) is added to a mononuclear cell concentrate and then activated by UVA light, thus forming covalent bonds between DNA strands. Infusion of these modified cells that are not able to replicate any more seems to lead to the elimination of pathogenic T-cell clones and clinical improvement in patients suffering from cutaneous T-cell lymphoma, graft versus host reactions, and various autoimmune diseases. The original method described by Edelson et al. (1987) was improved by the following modifications proposed by Andreu et al. (1994): i) by using a cell separator (COBE Spectra) that produced purer concentrate with less red blood cells absorbing UVA light. ii) By applying 8-MOP directly into the collection bag, the drug side effects due to the oral application of the thousandfold dose and varying serum levels were avoided. iii) By irradiating the concentrate after collection, all cells received the same irradiation dosage. We treated 2 men with cutaneous T-cell lymphoma, 2 women with atopic eczema and 1 man with severe pustular psoriasis with overall 123 extracorporeal photochemotherapy (ECPC) sessions. In addition to routine laboratory analysis, detailed characterization of lymphocyte subpopulations was carried out by flow cytometry to differentiate T-helper and T-suppressor cells and their activation (HLA-DR, CD 25), B, NK cells, and monocyte subpopulations. The following mediators soluble were analyzed as well: Il-2-receptor and as indicators of acute phase reaction Il-8, neopterin and Il-1 beta. We observed a good clinical improvement independent of no significant trend in the immunological phenotype of circulating blood leukocytes. Our results suggest that ECPC effects are not mediated by a systemic immune response or alternatively are not measured in the blood compartment.