Farmer’s lung is a hypersensitivity pneumonitis resulting from __________.


a. a type I hypersensitivity reaction to grass pollen
b. a type II hypersensitivity to red cells in the lung
c. a type III hypersensitivity to mold spores
d. a type IV hypersensitivity to bacterial antigens

Verified step by step guidance

1. Understand the concept of hypersensitivity pneumonitis, which is an inflammatory response in the lungs due to inhaled organic dusts.
2. Identify the types of hypersensitivity reactions: Type I (immediate), Type II (cytotoxic), Type III (immune complex-mediated), and Type IV (delayed-type).
3. Recall that Farmer's lung is associated with exposure to organic dusts, particularly mold spores found in hay or crops.
4. Recognize that Type III hypersensitivity involves immune complex formation, which is relevant to the inhalation of mold spores.
5. Conclude that Farmer's lung is most likely a Type III hypersensitivity reaction to mold spores, as it involves immune complex deposition in the lungs.

Key Concepts

Hypersensitivity Reactions

Hypersensitivity reactions are exaggerated immune responses to antigens that can lead to tissue damage. They are classified into four types: Type I (immediate), Type II (cytotoxic), Type III (immune complex-mediated), and Type IV (delayed-type). Understanding these types is crucial for identifying the mechanisms behind various allergic and autoimmune conditions, including Farmer's lung.

Type III Hypersensitivity

Type III hypersensitivity involves the formation of immune complexes between antigens and antibodies, which can deposit in tissues and trigger inflammation. This type of reaction is often associated with conditions like Farmer's lung, where exposure to mold spores leads to an immune response that damages lung tissue. Recognizing this mechanism is essential for understanding the pathology of hypersensitivity pneumonitis.

Farmer's Lung

Farmer's lung is a form of hypersensitivity pneumonitis caused by inhaling organic dust, particularly mold spores from hay or grain. It results in an inflammatory response in the lungs, leading to symptoms such as cough, fever, and difficulty breathing. Identifying the specific type of hypersensitivity involved helps in diagnosing and managing this occupational lung disease.