Direct measurements of the airway mucosal temperature will be performed before and at ten minutes after the SBP-Ag challenge. This miniature probe will be positioned in the airway lumen using an Olympus fiberoptic bronchoscope (model MP160F), and connected via a cable to a battery-operated thermometer (model FLL) manufactured also by Physitemp Instrument Inc. The probe (outside diameter of 0.4 mm) will be passed through the instrument channel (inner diameter: 2.0 mm) of the bronchoscope. By maneuvering the control knob of the bronchoscope, the blunted tip of the probe will be gently pressed against the airway mucosa at 5-6 different positions in segmental and sub-segmental bronchi, each for five to ten seconds. The entire protocol of the temperature measurement will require no more than 5 minutes to complete. The contact of the temperature probe on the airway mucosa should not cause any tissue damage, and is relatively non-invasive compared to other procedures involved in the routine bronchoscopy such as biopsy, cytology brushing, etc