Indicate whether each statement is true or false. If the statement is false, change the underlined word or phrase to make the statement true.


______ The tuberculin reaction is a type I hypersensitivity.

Verified step by step guidance

1. Identify the type of hypersensitivity reaction mentioned in the statement.
2. Recall the four types of hypersensitivity reactions: Type I (immediate), Type II (cytotoxic), Type III (immune complex-mediated), and Type IV (delayed-type).
3. Understand that the tuberculin reaction is a skin test used to determine if someone has been exposed to Mycobacterium tuberculosis.
4. Recognize that the tuberculin reaction is characterized by a delayed response, typically occurring 48-72 hours after exposure.
5. Conclude that the tuberculin reaction is a Type IV hypersensitivity, not Type I, and correct the statement accordingly.

Key Concepts

Hypersensitivity Types

Hypersensitivity reactions are classified into four types (I-IV) based on the immune mechanism involved. Type I hypersensitivity, also known as immediate hypersensitivity, is mediated by IgE antibodies and involves mast cell degranulation, leading to allergic reactions. Understanding these classifications is crucial for accurately identifying the nature of immune responses.

Tuberculin Reaction

The tuberculin reaction, also known as the Mantoux test, is a diagnostic tool for tuberculosis that assesses delayed-type hypersensitivity (Type IV). It involves the intradermal injection of purified protein derivative (PPD) from the tuberculosis bacterium, which triggers a localized immune response in sensitized individuals. This reaction is not an example of Type I hypersensitivity.

Immune Response Mechanisms

The immune response consists of various mechanisms that protect the body from pathogens. These include innate immunity, which provides immediate defense, and adaptive immunity, which develops over time and involves specific responses to antigens. Recognizing the differences between these mechanisms is essential for understanding how various hypersensitivity reactions occur.