DEMONSTRATION OF THE TH1 TO TH2 CYTOKINE SHIFT DURING THE COURSE OF HIV-1 INFECTION USING CYTOPLASMIC CYTOKINE DETECTION ON SINGLE-CELL LEVEL BY FLOW-CYTOMETRY

Objective: To characterize changes of Th1/Th2 cytokine production by p eripheral blood mononuclear cells (PBMC) that occur during the course of HIV infection by cytoplasmic cytokine staining on single cell level . Design and methods: Mitogen-stimulated PBMC from 16 healthy donors, 18 HIV-1-infected individuals without AIDS and 14 patients with AIDS w ere stained intracellularly with fluorescein-labelled MAb against inte rleukin (IL)-2, IL-4, IL-10 and interferon (IFN)-gamma. Additionally, co-staining of CD4+ T-cell, CD8+ T-cell, natural killer (NK) cell, B-c ell and monocytic markers was performed. Fluorescence staining was ana lysed by three-colour flow-cytometry. Results: A reduced percentage of IL-2 and IFN-gamma(Th1 type)-producing cells among CD4+ T cells from HIV-I-infected individuals could be demonstrated. There was a continuo us decrease of IFN-gamma-producing CD4+ T cells in the course of HIV i nfection and a dramatic reduction of IL-2-expressing cells among CD4T cells in patients with AIDS. In contrast to Th1 cytokines, the frequ ency of Th2 cytokine expressing cells among CD4+ T cells increased in HIV-infected individuals. The maximum frequency of IL-4-expressing cel ls among CD4+ T cells was seen in HIV-infected individuals without AID S, whereas the rate of IL-10-producing cells was highest in patients w ith AIDS. In HIV-infected individuals no significant proportion of Th0 cells expressing both Th1 and Th2 cytokines was detectable. In CD8+ T cells the percentage of IL-2 was expressing cells decreased continuou sly accompanied by a strong increase of the frequency of IFN-gamma-pro ducing cells. Conclusion: The decreased percentage of cells expressing IL-2 and IFN-gamma in conjunction with an increased proportion of IL- 4- and IL-10-producing cells among the CD4+ T cells in HIV-1-infected individuals demonstrate a Th1 to Th2 cytokine shift in the course of H IV infection on a single cell level. There was no evidence of a Th1 to Th0 cytokine shift. In addition to the loss of CD4+ T cells in HIV in fection, the qualitative changes of Th1/Th2 cytokine expression may se rve as a marker for progressive failure of cell-mediated immunity.