We assessed whether interleukin (IL)-10 and IL-12 production of blood mononuclear cells (PBMC) after lipopolysaccharide (LPS 0.1 microgram/ml, 1.0 microgram/ml) or phytohemagglutinin (PHA 5 microgram/ml) stimulation in advanced cancer patients with severe infections (IA, n=10) differs from those without infection (AC,n =10) or healthy controls HC (n=10). PBMCs in IA produced statistically higher median IL-12 levels than those in HC; LPS 0.1 (P=0.05), LPS 1.0 (P=0.019) and PHA (P=0.024). IL-10 production was always higher in AC than in HC. Both the IL-10 (LPS 1.0; P=0.018) and IL-12 (LPS 0.1;P =0.046) production of PBMCs were significantly higher in IA than one month afterwards. In conclusion, the PBMC production of IL-10 and IL-12 in advanced cancer patients with or without infection was not impaired but rather enhanced compared to that of HC. One month after infection, however, PBMC production clearly decreased, suggesting a kind of hyporeactivity.