IMMUNOLOGY

Detailed explanation-1: -After activation, the B cell undergoes differentiation and clonal expansion, which usually involves migration to germinal centers if the activation takes place in a lymph node. B cell differentiation is the process by which B cells change into different types, such as plasma cells and plasma blasts.

Detailed explanation-2: -The present data indicate that clonal expansion is a common occurrence in the B-cell repertoire of rheumatoid arthritis patients. These expansions involve both resting memory B cells and activated B cells, some of which are derived from the memory B-cell compartment.

Detailed explanation-3: -The clonal expansion initiates when antigen-specific naive T cells engage dendritic cells (DCs) bearing a cognate antigen in the secondary lymphoid organs such as lymph nodes (3, 4).

Detailed explanation-4: -The majority of mature B cells outside of the GALT reside within lymphoid follicles of the spleen and lymph nodes, where they encounter and respond to T cell–dependent foreign antigens bound to follicular dendritic cells (DCs), proliferate, and either differentiate into plasma cells or enter GC reactions.

Detailed explanation-5: -Clonal expansion of lymphocytes is a hallmark of vertebrate adaptive immunity. A small number of precursor cells that recognize a specific antigen proliferate into expanded clones, differentiate and acquire various effector and memory phenotypes, which promote effective immune responses.