Whole-body leucine kinetics and the acute phase response during acute infection in marasmic Malawian children

This study compared leucine kinetics and acute-phase protein and cytokine concentrations in three groups of Malawian children who were fed an isoenergetic, isonitrogenous diet: children with marasmus with (n = 25) and without (n = 17) infection and well-nourished children with infection (n = 13). The hypotheses tested were that whole-body leucine kinetics will be less in marasmic acutely infected children than in well-nourished acutely infected children but greater than in marasmic uninfected children. Children were studied after 24 h of therapy using standard ¹³C-leucine stable isotope tracer techniques. Well-nourished children with acute infection had greater leucine kinetic rates than did marasmic children with acute infection; nonoxidative leucine disposal was 153 ± 31 versus 118 ± 43 μmol leucine · kg^-1 · h^-1, leucine derived from whole-body proteolysis was 196 ± 34 versus 121 ± 47, and leucine oxidation was 85 ± 31 versus 45 ± 13 (p < 0.01 for all comparisons). Leucine kinetic rates were similar in marasmic children with and without acute infection. Well-nourished children with acute infection increased their serum concentration of five of six acute-hase proteins during the first 24 h, whereas marasmic children with infection did not have any increases. The serum concentrations f IL-6 were elevated in well-nourished and marasmic children with infection. These data suggest that the cytokine stimulus for the acute-phase protein kinetic response to acute infection is present in marasmic children but that the acute-phase protein metabolic response is blunted by malnutrition.