Objective: To determine whether or not soluble factors produced by peripheral blood mononulear cells (PBMC) can predict AIDS dementia.

Design and methods: PBMC were isolated from individuals with and without AIDS dementia complex (ADC) to determine if the levels of cytokines tumour necrosis factor (TNF)-[alpha] and interleukin (IL)-6, or the production of a neurotoxic substance, were significantly different. PBMC were studied after determining that the numbers of monocyte-derived macrophages isolated by adherence were highly variable from patients with ADC compared with individuals without ADC. We prospectively studied 16 AIDS dementia patients, 13 healthy HIV-seropositive individuals, and eight seronegative controls. Supernatants from PBMC were assayed for TNF-[alpha], IL-6 and alone for neurotoxicity on human neural cells in vitro.

Results: We observed a trend towards worse cognitive and motor performance in patients suffering from ADC but who had no opportunistic infections ('pure dementia'; n= 8). Levels of PBMC IL-6 were significantly higher in'pure dementia'patients. There was a trend towards lower levels of PBMC TNF-[alpha] in the group of patients who had both dementia and opportunistic infections compared with'pure dementia'patients. Supernatant from PBMC of ADC patients was significantly more neurotoxic than that from healthy HIV-seropositive individuals.

Conclusions: Macrophage isolation from PBMC of patients with ADC was altered. Soluble factors produced from PBMC were significantly more neurotoxic than soluble factors from PBMC of healthy HIV-seropositive individuals. PBMC production of TNF-[alpha] and IL-6 was not a significant predictor of ADC.