If you have psoriasis, one type of white blood cell, the B-cell, creates antibodies that destroy normal skin cells. Meanwhile, another type, the T-cell, makes too much of a protein called cytokine. This seems to affect the growth of skin cells. Normally, skin cells last about a month, then they die, flake off, and get replaced by new ones. If you have psoriasis, this cell turnover happens in days instead of weeks. Layers of skin build up, and there's more blood flow to the area, which leads to redness and swelling.