Assessment by flow cytometry of cytokine production in malnourished children

Abstract

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 (interleukin-2 [IL-2], gamma interferon [IFN-gamma], IL-4, and IL-10) in CD4+ and CD8+ cells and the activation capability (as indicated by CD69+ and CD25+ cells). CD4+ and CD8+ cells from malnourished children showed increased production of IL-4 and IL-10 cytokines and decreased production of IL-2 and IFN-gamma cytokines compared to that in cells from well-nourished, uninfected and well-nourished, infected children. In addition, malnourished children showed impaired activation capability, since the fluorescence intensity of CD69+ and CD25+ cells was lower than that in cells from well-nourished, uninfected and well-nourished, infected children. These results indicate that malnutrition alters the capacity of CD4+ and CD8+ cells to produce IL-2, IFN-gamma, 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.

FIG. 1.

Effect of malnutrition on percentages of cytokine-positive cells. The percentages of IL-2-, IFN-γ-, IL-4-, and IL-10-producing CD4⁺ cells from WN (n = 11), WNI (n = 12), and malnourished, infected (MN; n = 12) children are shown on the left. The percentages of IL-2-, IFN-γ-, IL-4-, and IL-10-producing CD8⁺ cells from the same groups are shown on the right. Data are based upon flow cytometric analysis of 10,000 events and are means ± standard errors. a, P < 0.005 (MN versus WN and WNI groups); b, P < 0.005 (MN versus WN and WNI groups); d, P < 0.005 (MN versus WN group) and P < 0.05 (MN versus WNI group); e, P < 0.05 (MN versus WN group) and P < 0.005 (MN versus WNI group); f, P < 0.005 (MN versus WN group) and P < 0.01 (MN versus WNI group); h, P < 0.005 (MN versus WN group) and P < 0.05 (MN versus WNI group).

FIG. 2.

Expression of activation antigens CD25 (a) and CD69 (b) by CD4⁺ and CD8⁺ cells from activated peripheral blood cells. Cells were activated with phorbol 12-myristate 13-acetate-ionomycin for 5 h at 37°C. Cells were stained and analyzed as described in Materials and Methods. Data are based upon flow cytometric analysis of 10,000 events and are means ± standard errors. Results are expressed as FI. (a) CD4, P < 0.01 (MN versus WN and WNI groups; CD8), P < 0.001 (MN versus WN and WNI groups). (b) CD4, P < 0.001 (MN versus WNI group) and P < 0.05 (WNI versus WN group); CD8, P < 0.001 (MN versus WN and WNI groups).