Innate and adaptive immune responses to ocular Acanthamoeba infections

The resurgence of Acanthamoeba keratitis in the USA and UK has increased the level of awareness of this contact lens-associated disease. Results from animal models have revealed that conventional T-cell-dependent immune mechanisms are ineffective in controlling corneal infections with Acanthamoeba spp. However, activation of the mucosal immune response in the form of secretory IgA antibodies in the tears is an effective method for preventing Acanthamoeba keratitis in animal models. Elements of the innate immune system, namely macrophages and neutrophils, are instrumental in mitigating and resolving Acanthamoeba keratitis in the Chinese hamster model of this disease. The unique biology of Acanthamoeba spp. and their residence in an immune-privileged tissue enhances their capacity to escape immunological detection and elimination.