Cytokine detection in HIV-1/HHV-8 co-infected subjects

In a previous work we have evaluated some immunologic and haematologic parameters of HIV-1 positive subjects co-infected with HHV-8. A worsening of these values were generally described in these patients as compared with those HIV-1 positive, but negative for HHV-8. Now we have studied the influence of HHV-8 co-infection of HIV-1 positive subjects on the production of some cytokines to make clear the question of its role in the immuno-deregulation of the above-mentioned subjects. In particular we have analysed serum levels of IL-4 and IL-10, Th2 type T cells cytokines, IFN-gamma, an indirect marker of Th1 cells activation and IL-18, a cytokine produced by monocytic-macrophagic cells, which is able to induce IFN-gamma production and Th1 T lymphocytes activation. No significant differences were found as regards the IFN-gamma serum levels (92.1 +/- 24.3 pg ml(-1) in the case of HIV-1 positive/HHV-8 negative subjects and 96.0 +/- 17.4 pg ml(-1) in those HIV-1 positive/HHV-8 positive). In healthy subjects the mean level of this cytokine was 17.6 +/- 5.2 pg ml(-1) (significant difference with both the former values at p < 0.001). Moreover IL-4 and IL-10, which were undetectable in healthy individuals, showed the following values in HIV-1 positive/HHV-8 negative subjects: 31.9 +/- 2.7 pg ml(-1) and 119.8 +/- 85.1 pg ml(-1) respectively and in HIV-1 positive/HHV-8 positive subjects: 30.4 +/- 4.8 pg ml(-1) and 69.4 +/- 65.3 pg ml(-1) (not significant differences). In contrast IL-18 reached a mean level of 1001.2 +/- 360.5 pg ml(-1) in HIV-1 positive/HHV-8 negative subjects, but showed a significant reduction in HIV-1 positive/HHV-8 positive subjects (737.6 +/- 284.3 pg ml(-1) --> p < 0.05) and presented very low levels in healthy individuals (21.3 +/- 30.3 pg ml(-1)). Moreover a significant correlation (-0.984 --> p < 0.001) was noticed between IL-18 reduction in HIV-1 positive subjects co-infected with HHV-8 and the degree of positivity of HHV-8. These data suggest that HHV-8 co-infection has no influence on the switch Th1 --> Th2 in HIV-1 positive subjects, but is able to reduce IL-18 production, useful for Th1 subset restoration.