Pneumocystis and interactions with host immune receptors

Introduction The majority of deaths from fungal infections occur in Africa. Pneumocystis is an unusual host-specific fungus that takes advantage of a weakened immune system and causes pneumonia in AIDS patients [1]. While Pneumocystis is thought to cause more than 200,000 AIDSrelated deaths annually, it also contributes to more than 50,000 non–AIDS-related deaths [2]. Recent epidemiological data suggest that Pneumocystis jirovecii pneumonia (PCP) cases are increasing in both England and the United States due to the increased use of immune suppression therapy for cancer, transplant, and inflammatory disorder patients [3, 4]. PCP faces diagnostic and treatment challenges that are significantly exacerbated in resource-poor settings and compounded by the fact that the organism cannot be cultured in vitro. This review briefly summarizes key mechanisms of host recognition of Pneumocystis spp. and how these systems fail in an immunocompromised host.