To test a new assay based on an ex vivo cytokine release from whole blood for the monitoring of immune changes in human immunodeficiency virus (HIV)-infected patients.

A pilot study of outpatients with HIV infection (n = 9) at a large academic hospital who were divided into three groups: HIV-infected patients on highly active antiretroviral therapy (HAART) with a CD4⁺ cell count >350/μL (group I) or a CD4⁺ cell count <350/μL (group II) and HIV-infected HAART-naïve subjects with a CD4⁺ cell count >350/μL (group III). All groups were compared with healthy volunteers (n = 3). The ex vivo cytokine release assay was performed in a three-step process: (1) blood collection, (2) whole-blood ex vivo incubation over 48 h without or with a standard set of well-defined recall antigens as comparable to those used formerly in the skin delayed-type hypersensitivity (DTH) test, (3) cytokine determination from the assay supernatant.

Under stimulated conditions, untreated HIV-infected patients with a CD4⁺ count >350/μL had similar interleukin-2 (IL-2) levels in the supernatant of the whole-blood incubation to HIV-infected patients on HAART with a low CD4⁺ count. Both groups revealed lower IL-2 levels in the supernatant than HIV-infected patients on HAART and with a CD4⁺ count >350/μL or healthy volunteers. The determination of interferon-γ and tumour necrosis factor-α in the supernatant showed a similar arrangement of cytokines between groups.

Our results suggest that this cytokine release assay could be a suitable tool to mirror the immunological responsiveness of patients with HIV infection in a gradual manner; further studies are required in order to assess its value in HAART monitoring.