Human dendritic cells pulsed with specific lipopeptides stimulate autologous antigen-specific T cells without the addition of exogenous maturation factors.

SUMMARY: Serum-free culture conditions to generate immature human monocyte-derived DC (Mo-DC) were optimized, and the parameters that influence their maturation after exposure to lipopeptides containing CD4(+) and CD8(+) T-cell epitopes were examined. The lipopeptides contained a single CD4(+) helper T-cell epitopes, one of a number of human leucocyte antigen (HLA)-A2-restricted cytotoxic T-cell epitope and the lipid Pam2Cys. To ensure complete maturation of the Mo-DC, we examined (i) the optimal lipopeptide concentration, (ii) the optimal Mo-DC density and (iii) the appropriate period of exposure of the Mo-DC to the lipopeptides. The results showed that a high dose of lipopeptide (30 microm) was no more efficient at upregulating maturation markers on Mo-DC than a low dose (6 microm). There was an inverse relationship between Mo-DC concentration and the mean fluorescence intensity of maturation markers. In addition, at the higher cell concentrations, the chemotactic capacity of the Mo-DC towards a cognate ligand, CCL21, was reduced. Thus, high cell concentrations during lipopeptide exposure were detrimental to Mo-DC maturation and function. The duration of exposure of Mo-DC to the lipopeptides had little effect on phenotype, although Mo-DC exposed to lipopeptides for 48 rather than 4 h showed an increased ability to stimulate autologous peripheral blood mononuclear cells to release interferon-gamma in the absence of exogenous maturation factors. These findings reveal conditions for generating mature antigen-loaded DC suitable for targeted immunotherapy.

Malnutrition as the main factor in morbidity and mortality of hemodialysis patients.

We evaluated the nutritional status of 120 hemodialysis patients using the urea kinetic model. Protein catabolic rate (PCR), an indirect measurement of dietary protein intake, and urea volume of distribution were calculated. Their mid-week predialysis BUN was targeted at 80 +/- 10 mg/dl. The risk factors for chronic hemodialysis patients were analyzed, and since the diabetic patients were unevenly distributed we took them out of the study. This report thus comprises 98 patients distributed in four groups according to their mean PCR and BUN: group 1, mean PCR of 0.63 g/kg/day and BUN of 51 mg/dl; group 2, mean PCR of 0.93 g/kg/day and BUN of 60 mg/dl; group 3, mean PCR of 1.02 g/kg/day and BUN of 79 mg/dl; group 4, mean PCR of 1.2 g/kg/day and BUN of 96 mg/dl. Patients in group 1 had a higher morbidity (number of hospitalizations and number of days in the hospital per patient per year) and a higher mortality (percent per year). The most common causes of hospitalization were infection and congestive heart failure. This group also had an unusually high incidence of pericarditis. Because their risk factors were similar to the other groups, the data suggest that malnutrition was the main cause of these patients' high morbidity and mortality. These patients must be considered at high risk and should be treated aggressively.