HLA-DR may play a role in antigenpresentation to activate T cells during the early stages of psoriasis pathogenesis.Moreover, although the peripheral blood CD19+ B cells may have been exhausted inerythrodermic psoriasis patients, we still observed a higher proportion of CD19+CD40+,CD19+CD80+, and CD19+CD11b+ B cells in the PBMCs compared to HCs, indicating that someof the B cells were still active. Here, CD40 is linked to psoriasis.