IFN-g mRNA expression was evaluated in nonstimulated peripheral blood mononuclear cells (PBMC) of HIV-infected and seronegative individuals using quantitative competitive and semiquantitative RT-PCR and the sensitivity of these methods was compared. A significant correlation was found between quantitative competitive and semiquantitative RT-PCR in samples of both HIV-seronegative (P = 0.004) and HIV-infected individuals (P = 0.0004). PBMC from HIV-infected individuals presented a remarkable increase of IFN-g mRNA expression, as determined by both types of RT-PCR methods. Semiquantitative RT-PCR even without an internal standard is also acceptable for measuring cytokine mRNA expression, but less reliable if small amounts are quantified. Moreover, we found that increased IFN-g mRNA expression is independent of CD4+ cell count in AIDS-free HIV-infected patients.
In HIV infection, the decrease in the number and functional activity of lymphocytes is accompanied by atopia and an increased level of total IgE and some specific IgE antibodies. This could be explained by the Th2 dominance induced by HIV replication and so a Th1-Th2 switch could have prognostic value. We investigated the characteristic T-helper phenotype dominance and its relationship to cytokine expression and IgE immune response in the early stage of asymptomatic HIV infection. In the separated lymphocytes of i. asymptomatic HIV positive persons; ii. HIV negative homosexuals; iii. atopic patients; and iv. healthy controls, expression of mRNA for IFNg (Th1) and IL-10 (Th2) were determined by semiquantitative RT-PCR. The serum level of antibodies for HIV 1/2 and total/specific IgE were also determined. Transcription of mRNA of IFNg and IL-10 were more pronounced in HIV positive and atopic groups than in the healthy control, without lymphocyte phenotype dominance. In HIV negative persons, however, a significant Th2 dominance was detected. There was no significant difference in the IgE level between the 4 investigated groups. In the HIV positive cases, IL-10 expression and total serum IgE do not support a switch to Th2 dominance. In the atopic group, aside from the total IgE level, down regulation of IFNg was not observed. These results suggest a general activation of the immune system in the early stage of HIV infection.
Effect of CCR-5 delta 32 heterozygosity in immunological protection was studied by a lymphocyte proliferation assay. Twenty of 86 HIV+ and eight of 32 healthy subjects showed heterozygous mutation (wt/mut) of the CCR-5 gene. Lymphocyte proliferation to pokeweed mitogen was found significantly higher (P < 0.005) in wt/mut versus wild type homozygous (wt/wt) HIV+ subjects in groups with CD4 > 500 and CD4 < 200 cell/ micro L. Phytohaemagglutinin induced stronger proliferation of cells from wt/mut HIV+ subjects with CD4 < 200 cell/ micro L (P = 0.03). Decline of lymphocyte response was more significant among wt/wt groups with different CD4+ cell counts than that between wt/mut groups to both mitogens. Reduced number of CCR-5 receptors on CD4+ cells may decrease the ability of HIV-1 envelope glycoproteins to transduce intracellular signals through CCR-5. Mutation in CCR-5 gene seems to have a benefit in preventing T-cells from HIV envelope-mediated immunopathogenic effects and maintain a relatively normal response to lectins.
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