Antibody-based immunotherapy of cryptosporidiosis.

Passive antibody immunotherapy (PAI) for cryptosporidiosis is a treatment strategy that has been actively pursued in laboratory studies and early-stage clinical studies for the last decade. Several experimental approaches have been initiated, including use of bovine colostrum and colostral antibodies (hyperimmune and natural), monoclonal antibodies, chicken egg yolk antibodies, and even orally administered human plasma antibodies. Most studies have employed oral administration to treat or prevent this intestinal infection. The interest in this treatment strategy has been sparked by the lack of an effective or approved therapy, increased awareness of the widespread nature of this parasite, epidemiological evidence that humoral immunity plays an important role in host resistance, and several early case reports of antibody therapy in which remarkable resolution of the disease was observed. Most studies using a variety of preparations of antibodies administered to animals and humans have shown some degree of efficacy, though the responses have been, for the most part, partial rather than complete resolution of the disease. This chapter examines critically the scientific rationale and the evidence for PAI for cryptosporidiosis, including practical considerations and future approaches.