Physiology of immune competence

When evaluating a child with recurrent infection or suspected immune dysfunction it is important to keep in mind the different components of a fully competent immune response. There are three main parts. A healthy and competent immune response requires an effective (i) barrier to infection (ii) innate immune response and (iii) adaptive immune response. An understanding of these discrete systems and how they interact allows clinicians to undertake investigation and management in a strategic manner, moving beyond a 'tick box' approach to immune dysfunction. This review will outline different elements of the immune system, with specific reference to defects that can lead to disease in humans.