The production of interleukin-2 (IL-2) and interleukin-6 (IL-6) by peripheral blood mononuclear cells (MNC) was assessed in patients with Alzheimer's disease (AD) who were subdivided into two groups--mild and moderately-severe--according to the severity of the disease, probable vascular dementia (VaD) patients and elderly control subjects. No differences in IL-2 secretion were found between mild AD patients and controls. However, there was a significant increase in IL-2 production both in the moderately-severe AD group and in the VaD group. IL-6 levels in AD patients of both groups were similar and significantly higher than those of VaD and controls. Our results suggest that increased levels of IL-2-production correlate with severity of the dementia, whereas increased levels of IL-6 production seem to be related to AD and thus may play a role in AD pathogenesis.