Lipopolysaccharide (LPS) is an endotoxin created by some gram-negative (-) bacteria that commonly causes fever in humans. Lipopolysaccharide is what type of molecule?

• A. Endogenous pyrogen.
• B. Exogenous pyrogen.
• C. Pathogenic pyrogen.
• D. External pyrogen.

Answer: (B)

Verified step by step guidance

1. Understand the definition of a pyrogen: Pyrogens are substances that can cause fever by triggering the body's immune response.
2. Differentiate between endogenous and exogenous pyrogens: Endogenous pyrogens are produced within the body, typically by immune cells, while exogenous pyrogens are external substances that enter the body and cause fever.
3. Identify the source of lipopolysaccharide (LPS): LPS is a component of the outer membrane of gram-negative bacteria, making it an external substance to the human body.
4. Classify LPS based on its origin: Since LPS is produced by bacteria and not by the human body, it is considered an exogenous pyrogen.
5. Conclude that LPS, being an external substance that causes fever, fits the definition of an exogenous pyrogen.