As humoral responses progress, the average affinity of the antibodies produced rises, in a process known as "affinity maturation." This seems at odds with at least one aspect of the clonal selection hypothesis, since the notion of "clonal integrity" implies that the progeny of an activated lymphocyte retain the specificity the original, pre-immune, antigen receptor. So here are the questions:
What is the basis for "affinity maturation" in humoral responses?
Does this contradict the tenets of clonal selection? Perhaps a bit more broadly, does this force rejection of the clonal selection hypothesis as a viable model to explain the cellular basis for specificity of adaptive immunity?
At the end of the response, you should raise an issue you are curious about related to the topic in the question.
Affinity Maturation in Humoral Response
Affinity maturation is a really beneficial phenomenon of our humoral response. It is the process that B-cells undergo during an immune response. Generally speaking, when B-cells get activated, they secrete a soluble form of their receptors called antibodies. These antibodies bind to pathogens, inactivating them, or else identify them to phagocytes and other defense systems so that they can be eliminated. Next, the B-cells clone themselves. This is the basis of clonal selection. In other words, all the progeny of a given activated B-cell should be identical clones.
Therefore, how can we explain the production of a new line of B-cells that actually ...