Question

Once activated, what does the B-cell do during its proliferation within the germinal center, and how does this proliferation event help “shape” the antibody to be better and polymorphic?

Answer 1

B cells or B lymphocytes are type of WBC which helps in humoral immunity by secreting the antibodies.  

B cells mature in bone marrow after which they are carried to spleen and lymph nodes by blood where there are constant supply of antigens for activation of B cells. Therefore, in spleen and lymph nodes B cells are activated.

After activation of B cells, the proliferation of these B cells takes place in spleen to form terminal centers in secondary lymphoid organs such as tonsils. The stimulation of the B lymphocyte with CD40 by its ligand CD154 causes proliferation, differentiation and survival of these B cells.

This binding of CD40 by its ligand CD154 triggers signal transduction pathways . After this binding, the tumour necrosis factor receptor associated factors ( TRAFs) associate with cytoplasmic domain which induces phosphyrlation by tyrosine kinase along with activation of stress activated protein kinase . It also cooperates with other B cell antigen receptors, cytokines,adhesion molecules, other members of TNF.The binding of CD27 by CD70 increases B cell proliferation and differentiation.

This is how the proliferation event shape the antibody to be better and polymorphic.