There are two types of B cells in the lymph nodes those that learn to manufacture new antibodies and those that go out and do the fighting. This is evolution on the fly. New genes make new antibodies as the individual learns about new infections. In babies who nurse, there are generalized antibodies from the Mother's milk to start the protection (first 24+ hours of nursing), and then the learning takes over. This is why babies average five colds a year and adults have one new and then.-http://medicalxpress.com/news/2013-03-evolution-antibody-factory-immune-cells.html-Looks like a clever design to me.