Phenotypic and functional considerations in the evaluation of immunity in nutritionally compromised hosts

It is well established that proper nutrition is critical to the development of an effective immune system and to enhance the natural immunosurveillanc e and its effector mechanisms. This enhancement could be mediated either by increasing the frequency and absolute numbers of effector cells or by up-r egulation of the cellular mechanisms by which these effector cells carry ou t their functions. Even in the Western world, large sectors of society ofte n remain undernourished and show suboptimal immune responses, but the relat ionship between nutrition and immunity is best seen in developing and under developed countries. Although there are many large-scale field studies that investigate the issue of nutrition and immunity, there are relatively few data that go beyond descriptive measurements and directly address how well the immune system functions. This review summarizes interactions between nu trition and immunity and focuses on practical aspects for evaluation of the immune function in the field.