Question

Which one of the following statements about central memory T cells is true?

• A. They reside in the secondary lymphoid organs
• B. They exit the lymph node and circulate in the body
• C. They settle in the peripheral tissue
• D. They reside in the bone marrow

Hint:

Central = Lymphoid center. Effector = Out in the field (tissues).

Answer 1

The Correct Option is A

Step 1: Concept
Memory T cells are divided into Central Memory ($T_{CM}$) and Effector Memory ($T_{EM}$) based on their homing receptors.

Step 2: Analysis
$T_{CM}$ cells express CCR7 and CD62L, which allow them to home to and reside within secondary lymphoid organs like lymph nodes.

Step 3: Reasoning
In contrast, Effector Memory T cells ($T_{EM}$) lack these receptors and circulate through or settle in non-lymphoid peripheral tissues.

Step 4: Conclusion
Central memory T cells reside in secondary lymphoid organs. Final Answer: (A)