Most B and T lymphocytes in the circulation appear as small, inactive cells, with little cytoplasm, few cytoplasmic organelles, and nuclei containing condensed inactive chromatin. Yet these cells comprise the adaptive immune response, without which individuals die in infancy. What is the explanation for this apparent dichotomy?

Question

Quizplus · Accepted Answer

The Answer is B and T lymphocytes are a heterogeneous population, comprised of cells that each express a unique antigen receptor. As a consequence, only a small number of B and T lymphocytes will respond to any particular pathogenic infection. The vast majority of the circulating cells will never encounter the pathogen that binds to their antigen receptor; hence these cells remain in a naive, inactive state.

Most B and T Lymphocytes in the Circulation Appear as Small