Lymphocyte transformation test in patients with nickel sensitivity: an aid to diagnosis.

Peripheral blood lymphocytes from 16 patients with a positive patch test to 2.5% nickel sulphate (NiSO4) and 18 healthy controls were tested by the lymphocyte transformation technique where NiSO4 in six different concentrations was used and tested after various days of culture. Lymphocytes from all except one of the patients showed a significantly greater response than that of the controls. Lymphocyte transformation as measured by increased DNA synthesis seems to be a valuable tool for investigating the problems arising from false-positive or false-negative patch tests. With these data we have defined certain criteria for in vitro reactivity that should be fulfilled. Lymphocytes from controls responded non-specifically to high concentrations of NiSO4. Cord blood lymphocytes from 4 newborn infants could also be activated by NiSO4, thus confirming the assumption that NiSO4 is a weak mitogen.