In chronic and aggressive periodontitis plasma cells reactive to HtrA1 were more represented and strongly stained than in gingivitis (Fig. 2C, 2D), with an increasing intensity of the immunostaining from chronic (Table 3, Figs. 2C, 3B) to aggressive (p<0.001) (Table 3, Figs. 2D, 3B) periodontitis. The gene discussed is HTRA1; the disease is periodontitis.