In this study, we used a case-control approach to examine the ratios of CD19+ B cellsubsets (i.e., CD19+CD40+, CD19+CD44+, CD19+CD80+, CD19+CD86+, CD19+CD11b+, andCD19+HLA-DR+ B cells) in PBMCs from psoriasis patients with the vulgaris, erythrodermic,pustular, and arthropathic clinical subtypes, as well as in the skin lesions andnon-lesion areas of 7 erythrodermic psoriasis patients. The gene discussed is CD40; the disease is psoriasis.