Biotech Values

[vinmantoo]

The CD40/CD40L interactions from these now activated CD4 T cells (with cytokine help also), in turn cause Ig class switching so that these interactions reinforce each other.

Doc328, thanks for that very nice summary. Let me add that once the B cell has rearranged and class switches, there is a selection where cells whose BRC binds the antigen the tightest are stimulated to divide more. That means those with the strongest binding start predominating in the population. In addition, cells employ a targeted mutagenesis of the DNA segments which encode the variable regions of the antibody. Theses small changes can produce progenitor cells with stronger, the same or weaker antigen binding, and again the stronger binders will proliferate more. Thus, the antibody response gets stronger and more potent with time. Of course this antibody response needs to be eventually dampened down or resources will be wasted or possibly autoimmune responses can arise, but that is another story.