Journal Article
Review
Add like
Add dislike
Add to saved papers

Chapter 19: Hypersensitivity pneumonitis.

Hypersensitivity pneumonitis (HP), also referred to as extrinsic allergic alveolitis, is characterized by non-IgE-mediated inflammation of the parenchyma, alveoli, and terminal airways of the lung initiated by inhaled antigens in a susceptible host. Etiologic agents of HP are either organic high molecular weight compounds such as bacteria, fungi, amoebae, plant, and animal proteins or inorganic low molecular weight haptens such as isocyanate and drugs including amiodarone, nitrofurantoin, and minocycline. Six significant predictors have been identified that provide ∼95% diagnostic accuracy. These six predictors are (1) exposure to a known offending allergen, (2) positive precipitating antibodies to the offending antigen, (3) recurrent episodes of symptoms, (4) inspiratory crackles on lung auscultation, (5) symptoms occurring 4-8 hours after exposure, and (6) weight loss. HP is staged into acute, subacute, and chronic. In the acute stage after direct exposure to the antigen, there is fever, chills, nonproductive cough, dyspnea, malaise, and myalgias, all resembling influenza. However, if obtained, a chest radiograph shows nodular infiltrates, and pulmonary function testing is restrictive (unless the cause is avian in which obstruction or obstruction with restriction is present). In the chronic stage, fever and chills are absent, but weight loss can occur. The immunologic response includes activated macrophages and CD8(+) cytotoxic lymphocytes, and bronchoalveolar lavage fluid reveals marked lymphocytosis with a ratio of CD4(+) cells to CD8(+) cells <1. Activated macrophages have increased expression of CD80/CD86, and T cells have increased expression of its counter-ligand CD28, evidence for heightened antigen presentation.

Full text links

We have located links that may give you full text access.
Can't access the paper?
Try logging in through your university/institutional subscription. For a smoother one-click institutional access experience, please use our mobile app.

Related Resources

For the best experience, use the Read mobile app

Mobile app image

Get seemless 1-tap access through your institution/university

For the best experience, use the Read mobile app

All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.

By using this service, you agree to our terms of use and privacy policy.

Your Privacy Choices Toggle icon

You can now claim free CME credits for this literature searchClaim now

Get seemless 1-tap access through your institution/university

For the best experience, use the Read mobile app