Lymphocyte subset changes in blood and gastrointestinal mucosa after oral nickel challenge in nickel-sensitized women

This study investigates lymphocyte subsets in both the gastrointestinal muc osa and blood, in patients with nickel allergic contact dermatitis, after 1 0 mg oral nickel challenge (double-blind, placebo-controlled). 6 such patie nts with cutaneous symptoms induced only by skin contact with nickel (group A), 6 with a flare-up of cutaneous symptoms after food nickel ingestion (g roup B) and 6 healthy controls (group C) were enrolled. Blood lymphocyte su bsets (CD3, CD45RO, CD8) were analyzed before and after 4 and 24 h from the challenge (test 1, 2, and 3), and intestinal biopsies were performed 2 day s later. Challenges were positive in group B and negative in group A and co ntrols. Serum and urine nickel levels significantly increased after nickel ingestion, with no differences between the 3 groups. At test 3, a significa nt decrease of the all CDs studied was found in group B. Biopsies of this g roup showed higher levels of CD45RO+ cells in the lamina propria and in the epithelium and lower levels of epithelial CD8+ lymphocytes. This study con firms that ingested nickel may induce Rare-up of cutaneous reactions in som e nickel-allergic patients, independently of the degree of sensitization an d the intake of metal. In these patients, oral nickel stimulates the immune system, inducing maturation of T lymphocytes from virgin into memory cells ; these latter cells seem to accumulate in the intestinal mucosa. The immun oreaction also involves CD8+ cells, whose role is not yet clear.