Lipopolysaccharide (LPS) is an endotoxin found on the surface of gram-negative bacteria. LPS can cause the body to enter septic shock and result in multi-system organ failure. Because of its severe effects, it is important that the immune cells react quickly to LPS. LPS is an antigen that can directly trigger antibody secretion once it comes in contact with a B cell. LPS is what kind of antigen?

• A. T-independent antigen.
• B. Direct antigen.
• C. T-dependent antigen.
• D. B-independent antigen.

Answer: (A)

Verified step by step guidance

1. Understand the role of Lipopolysaccharide (LPS) in the immune response. LPS is a component of the outer membrane of gram-negative bacteria and acts as an endotoxin.
2. Recognize that LPS can directly trigger antibody secretion from B cells without the need for T cell help. This characteristic is crucial in identifying the type of antigen.
3. Learn the difference between T-independent and T-dependent antigens. T-independent antigens can activate B cells without T cell assistance, while T-dependent antigens require T cell involvement for B cell activation.
4. Consider the options provided: T-independent antigen, Direct antigen, T-dependent antigen, and B-independent antigen. Focus on the ability of LPS to activate B cells directly.
5. Conclude that LPS is a T-independent antigen because it can stimulate B cells to produce antibodies without the need for T cell help, fitting the definition of a T-independent antigen.