Parasitic protozoa and helminths: biological and immunological challenges

Glutamine and arginine: immunonutrients for improved health

There is considerable literature demonstrating that specific nutrients can influence immune function in health and disease. This review will examine the literature and the rational for classifying two amino acids, glutamine (gln) and arginine (arg), as "immunonutrients" during infections. An understanding of immune defenses during infections (virus, parasite, bacteria, protozoa) and metabolism of gln and arg by immune cells is necessary to understand how these nutrients can influence specific functions of the immune system. This review focuses on several key clinical studies in immunosuppressed individuals (burn patients, individuals with cancer and HIV infection, and those undergoing surgery or who have experienced major traumas) that have tested the hypothesis that the provision of gln and/or arg is beneficial to immune function and clinical outcome. These clinical studies support the dietary "essentiality" of these two nutrients for improving immune responses in most immunosuppressive states associated with high rates of infection. However, the role of these nutrients in modulating the immune changes that occur with exercise in healthy athletes demands additional experiments.

Vaccines against human parasitic diseases: an overview

There are no vaccines currently available to control the major human parasitic diseases, although there is evidence of acquired immunity and resistance to reinfection in most of the parasitic infections. The present manuscript concentrates on the vaccines for parasitic diseases that are in the most advanced stages of development: malaria, leishmaniasis and schistosomiasis. Vaccines for malaria and leishmaniasis have been taken to clinical trials while vaccines for schistosomiasis are being considered for Phase I (assessment of safety and immune responsiveness in volunteers). We have attempted to give a factual account of the present status of knowledge of vaccines against human parasitic diseases, emphasizing both the successes and setbacks. We do not intend to cover the enormous literature in the field but have concentrated on the most promising antigenic preparations. Finally, some new approaches for the development of vaccines are discussed including nucleic acid vaccines and the use of cytokines as adjuvants.