Subjects will complete a physical exam. (Table 1) Methods Skin Testing Medications known to affect skin test response will be withheld prior to testing. Ppt and intradermal testing will be done with Dp dust mite allergen, saline, and histamine controls. Criterion for a positive ppt result is a wheal diameter 3 mm or greater than the saline negative control. Criterion for a positive intradermal skin test result is a wheal 6 mm or greater than the saline negative control. Allergen and control skin tests are read at 15 minutes. Ppt will use standardized Dp (10,000 AU/mL; Greer Laboratories, Lenore, NC), glycerinated phenol saline (negative) and histamine (positive) controls (histamine base= 1.8 mg/mL) on the upper back. The minimum positive control will be a 3mm wheal diameter.