The lymphoid tissue of Waldeyer's ring, and particularly the nasopharyngeal tonsil
(adenoids), appears to be functionally comparable to nasal-associated lymphoid tissue in
rodents. Antigen-stimulated lymphoid follicles give rise to:(a) clonal B-cell expansion;(b) B-
cell receptor affinity maturation;(c) positive selection of B cells according to receptor affinity
for antigen;(d) differentiation to B memory cells and plasma cells; and (e) variable induction
of the joining (J)-chain gene. B-cell differentiation is also important to promote downstream …