Concluding remarks

Recent studies have documented the usefulness of employing immunocompetence as a functional measure of nutrition (17). In growing infants, it may be a sensitive index of imminent failure to thrive and of infectionrelated morbidity.

Obviously, there are many unanswered questions. Many of the immunologic processes act in unison and often interact in a synergistic fashion. Impairment of one facet of immunity may be of little functional consequence for the host if other components are intact. The specificity of tests of immunocompetence is debatable. Other disorders, often clinically apparent, as well as infection, can depress immune responses. The threshold of clinically relevant immuno-deficiency is ill-defined. How much reduction in the number of circulating T cells is biologically significant? Does a 50 per cent decrease in serum complement C3 concentration predispose to more frequent or severe infection? Infection often complicates malnutrition and can suppress immunity.

The answers to these and other crucial questions must await further investigation. Nevertheless, existing knowledge indicates that the assessment of immunocompetence by the methods currently available provides useful prognostic information in relation to nutritional deficiency and in the evaluation of nutrition intervention programmes.