Malnutrition in children is associated with an increased risk of infection and death. Multiple abnormalities in the immune response, including cytokine production, in protein energy-malnourished children have been described and could account for the increased severity and frequency of infections. In this study, we used flow cytometry to investigate the effects of malnutrition on the production of cytokines ؉ and CD8 ؉ cells to produce IL-2, IFN-␥, IL-4, and IL-10 in response to stimulus. We concluded that both cytokine production and activation capacity were impaired in malnourished children. This functional impairment may be involved in the failure to develop a specific immune response and the predisposition to infection in these children.Malnutrition remains one of the most common causes of morbidity and mortality among children throughout the world (1). It is estimated that, in developing countries, more than one-quarter of all children younger than 5 years of age are malnourished (37). Malnutrition has been identified as an important risk factor for predisposition to infections leading to death (36). The strong association between malnutrition and infections has been established through epidemiologic studies conducted in several different countries. The severity of malnutrition determines the risk of death and/or severity of infections (17).Multiple abnormalities in the immune response, including T-cell number, ratio of T-cell subsets, NK cell activity, and cytokine production, have been described in connection with protein energy malnutrition. Nevertheless, results of studies investigating these topics are controversial (13,23,29). Several studies on the effects of malnutrition at the immunological level have been carried out with humans and experimental animals. These studies indicate that malnutrition decreases T-cell function, cytokine production, and the ability of lymphocytes to respond appropriately to cytokines (8,20,6).

Protein-energy malnutrition is the primary cause of immune deficiency in children across the world. It has been related to changes in peripheral T-lymphocyte subsets. The aim of the present study was to evaluate the effects of infection and malnutrition on the proportion of peripheral-lymphocyte subsets in well-nourished non-bacterium-infected (WN), well-nourished bacterium-infected (WNI), and malnourished bacterium-infected (MNI) children by flow cytometry. A prospectively monitored cohort of 15 MNI, 12 WNI, and 17 WN children was studied. All the children were 3 years old or younger and had only bacterial infections. Results showed a significant decrease in the proportion of T CD3 ؉ (P < 0.05 for relative and P < 0.03 for absolute values), CD4 ؉ (P < 0.01 for relative and absolute values), and CD8 ؉ (P < 0.05 for relative values) lymphocyte subsets in WNI children compared to the results seen with WN children. Additionally, B lymphocytes in MNI children showed significant lower values (CD20 ؉ P < 0.02 for relative and P < 0.05 for absolute values) in relation to the results seen with WNI children. These results suggest that the decreased proportions of T-lymphocyte subsets observed in WNI children were associated with infection diseases and that the incapacity to increase the proportion of B lymphocyte was associated with malnutrition. This low proportion of B lymphocytes may be associated with the mechanisms involved in the immunodeficiency of malnourished children.Protein-energy malnutrition is a public health problem in developing countries. Around the world, each year 12 million children under 5 years old die due to the relationship between malnutrition and infectious diseases. Even if malnutrition is very extensive in developing countries, it is rarely considered one of the main mortality causes. However, recent studies indicated that malnutrition in developing countries is an associated death cause in the deaths of more than 50% of children (34). In community studies, a clear relationship between weight decrease and increase of mortality risk has been observed. Also, a solid and systematic relationship between malnutrition and a higher risk of respiratory and diarrhea infections have been detected (27). Several authors have pointed out that malnutrition is the primary cause of immunodeficiency in the world (8,12,32), and it has been related to changes in cellular immunity (8, 29) and changes in peripheral-lymphocyte subsets (mainly CD3 ϩ , CD4 ϩ , and CD8 ϩ ). Nevertheless, results of studies investigating this topic are controversial. In some studies an increase of lymphocyte proportion has been observed; meanwhile, other studies show a decrease in lymphocyte proportions (4,7,10). In a previous study Nájera et al. found no changes in lymphocyte T subsets when malnourished and well-nourished children with bacterial infections were compared (18). These controversial results may be associated with several factors, such as the methods used, the type and degree of malnutrition, and the infection type. For th...