Th e order of chapters in the seventh edition has been revised
to better reflect the sequence of events that occurs naturally
during an immune response in vivo. Th is off ers instructors
the opportunity to lead their students through the steps of
an immune response in a logical sequence, once they have
learned the essential features of the tissues, cells, molecular
structures, ligand-receptor binding interactions, and
signaling pathways necessary for the functioning of the immune
system. Th e placement of innate immunity at the forefront
of the immune response enables it to take its rightful place
as the fi rst, and oft en the only, aspect of immunity that an
organism needs to counter an immune insult
