An understanding of the mode of action and rational clinical
application of immunomodulatory drugs requires good working knowledge of the body system that the agents are intended to
manipulate. Immunology is a rapidly evolving science and our
increasing depth of understanding has helped to explain the
action of old drugs and to develop new therapies based on inhibition
of recently discovered cellular and molecular pathways. In
the past decade, there have been two key areas in which there has
been rapid advance in understanding the interaction between
the innate and adaptive immune system and the key role
of regulatory T cell subsets in control of the adaptive immune
response.