Figure 1.

A, Proliferation of PBMC of patients with double‐positive PT to Ni and Pd (group 1), positive PT only to Pd (group 2), and negative PT to Ni and Pd (group 3) after 6 days of stimulation with Ni in three different concentrations. SI is given; a SI > 3 is regarded as positive reaction (red line); positive control PHA gave no differences in the three groups; *P < .05. B, Proliferation of PBMC of patients with double‐positive PT to Ni and Pd (group 1), positive PT only to Pd (group 2), and negative PT to Ni and Pd (group 3) after 6 days of stimulation with PdCl₂ in nine different concentrations. SI is given; a SI > 3 is regarded as positive reaction (red line); positive control PHA gave no differences between the three groups; *P < .05. PBMC, peripheral blood mononuclear cells; PHA, phytohaemagglutinine; PT, patch test; SI, stimulation index