UVB-induced Treg Cells Exert Antigen-specific Suppression Through LAG-3

The goal of this clinical trial is to compare the immune cell population in blood of the participants with psoriasis/atopic dermatitis before and after UVB treatment. The main questions it aims to answer are: 1. how immune cells in the PBMCs from blood of participants are affected by UVB treatment 2. will UVB treatment expand the antigen-specific Treg cell population 3. will UVB treatment enhance the suppressive function of Treg cells Participants giving written informed consent will donate their blood (20 ml) before UVB treatment begins. After 8 to 10-week treatment course, the participants will donate their blood (20 ml) again. Researchers will compare immune cell population changes in the PBMCs of participants before and after UVB treatment. In addition, researchers will purify Treg cells from participant blood before and after UVB treatment to test their suppressive activity by ex vivo suppression assay.