ABSTRACT
I. Introduction The immune system comprises a complex organization of innate and adaptive host defenses involving multiple organs. These include organ systems with mucosal surfaces, such as the respiratory and alimentary tracts, that encounter the bulk of the microbes to which we are exposed. The circulatory and lymphatic systems are classically thought of as contributing cellular and humoral adaptive immune mechanisms against infection. Nontraditional ‘‘immune’’ organ systems such as the central nervous and endocrine systems also participate in immunity against infection. As our understanding of immune defense mechanisms deepens, we come to see that the defense against most microorganisms is usually multifactorial. Thus, while it may be somewhat artificial to focus on a single aspect of the immune response in the defense against an infectious agent, such an approach may be useful in helping us to understand how various elements of host immunity can bring about control of an infection. In this chapter, we summarize the evidence that antibody-mediated immunity is critical in protecting against the development of Pneumocystis pneumonia (PcP), knowing full well that many components of the immune system interact to control disease produced by Pneumocystis. We also briefly describe examples of antibody-mediated immunity against other fungi as models that may provide a guide for future studies on Pneumocystis.
