T Cell Effector and Regulatory Mechanisms in Asthma

Summary

The specific hypothesis for this study is that there are fundamental differences in T effector and T regulatory cell responses in the lung to allergens in allergic asthma (AA) when compared to allergic nonasthmatics (ANA) that account for the difference in clinical responses. We will address this by comparing T cell responses in AA versus ANA subjects. These experiments will correlate T cell responses with measures of airway physiology using state-of-the art lung imaging and examine mechanisms controlling T cell activation in the airways of AA and the function of airway T regulatory cells during AA.

Conditions

• Asthma
• Allergies

Interventions

BIOLOGICAL

Bronchoscopy, Segmental Allergen Challenge and Broncheoalveolar Lavage

On the day of the first bronchoscopy,BAL will first be performed in the lingula without instillation of diluent or allergen.Then, a 2-ml aliquot of isotonic diluent is instilled into the right upper lobe. Then, the procedure will be repeated in the right middle lobe with instillation of 2-ml of standardized cat or mite allergen solution.A "test dose" concentration of allergen is administered first consisting of 2 ml of allergen at 1/10th(Cat,D.farinae) or 1/30th(D. pteronyssinus) the threshold concentration.If on visual inspection through the bronchoscope, there is no evidence of mucosal inflammation after two minutes, a second segmental allergen challenge will be done in the right middle lobe using 2-ml of full-dose allergen at the threshold concentration(Cat,D.farinae) or 1/3th the threshold concentration(D.pteronyssinus).This dose will be predetermined by quantitative skin prick testing.A second bronchoscopy is performed 24 hours after delivery of allergen extract and diluent.

PROCEDURE

PET-CT imaging(13NN perfusion/ventilation, 18FDG inflammation, and CT imaging)

Imaging is first performed the evening prior to the 1st bronchoscopy.An IV catheter is placed.An attenuation correction is performed to remove image distortion using a chest CT volumetric scan.Subjects are instructed to exhale to the same mean lung volume of the CT scan and hold their breath for 20sec.Simultaneous with apnea,13NNsaline is injected IV and a series of PET scans is acquired.Then subjects resume breathing, matching their previous respiratory rate and tidal volume.After 3 min,within an interval of 1 min,spirometry and 2 deep inhalations are performed,followed by 1 min of washout. For the second imaging visit, which will occur 24 hour later, the imaging sequence will be repeated as described above, but will also include 18FDG infusion.At least 30 minutes after the 13NN injection,10mCi of 18FDG is infused. Then, images are collected over a 75 minutes.Venous blood is sampled at 5 different time points over a 40-45 minute time window to determine plasma radioactive levels.

Sponsors & Collaborators

• National Institute of Allergy and Infectious Diseases (NIAID)

  collaborator NIH

• Andrew D. Luster, M.D.,Ph.D.

  lead OTHER

Principal Investigators

• Andrew D Luster, M.D., Ph.D. · Massachusetts General Hospital

Study Design

Allocation

NA

Purpose

BASIC_SCIENCE

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

18 Years

Max Age

50 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2012-09-30

Primary Completion

2016-09-30

Completion

2016-09-30

Countries

• United States

Study Locations