Impairement of thymus derived rosette forming cells during photochemotherapy (psoralen--U.V.A.).

Lymphocyte subpopulations were studied in 45 PUVA treated patients and in 45 controls matched for sex and age. The results demonstrate that, in vivo PUVA induces a decrease in the capacity of the E-Rosette formation by lymphocytes separated from the peripheral blood. However, the circulating lymphocytes count remains unchanged. Mitogen induced blastogenesis is not affected. No correlation is found between the decrease in the level of E-rosettes, the disease which motivated PUVA therapy, the energy in UVA and the number of irradiation. Electrical and/or chemical modifications on the cell surface of the lymphocytes during PUVA therapy are postulated to explain this phenomenon.