Depigmented-polymerised house dust mite extract stimulates significantly less PBMC proliferation than unmodified native extract. PBMC (2x106/mL) were cultured with depigmented-polymerised (Depig-pol), depigmented (Depig) or native HDM extracts at different concentrations for different times: proliferation was assessed by thymidine incorporation, as described in Methods. N = 6. Statistical analysis by ANOVA. A Time course for proliferation of Depig-pol, Depig and native HDM extract-stimulated PBMC at a concentration of 100 μg/mL of each extract. p value for Depig-pol vs. native extract. B Dose-response for proliferation of Depig-pol, and native HDM extract-stimulated PBMC at day 7.