Elevation of Gal-9 in plasma of HIV⁺ individuals and up-regulation of p21 in CD4⁺ T cells after stimulation with Gal-9. (A) Detected levels of plasma Gal-9 from 30 HIV⁺ individuals with a viral load of less or more than 10 000 copies/mL. (B) RT-PCR reflecting β-actin, p53, and p21 gene expression in activated CD4⁺ T cells stimulated with Gal-9 (1 μg/mL; +Gal-9) or in the absence of Gal-9 (−Gal-9) for 2 hours before total RNA isolation. (C) Quantitative CDKN1A mRNA fold expression from activated CD4⁺ T cells after stimulation with Gal-9 (1 μg/mL) for 2 hours in vitro compared with CDKN1A mRNA expression in CD4⁺ T cells in the absence of Gal-9 from the same individual. Significance was tested using Wilcoxon signed rank test. (D) Correlation between CDKN1A mRNA fold expression from CD4⁺ T cells in the presence of Gal-9 (1 μg/mL) and resistance to HIV-1 infection. Resistance to infection was measured by intracellular staining for viral p24 antigen using flow cytometry on CD4⁺ T cells infected with R5-tropic HIV-1 isolate in the presence of Gal-9 (1 μg/mL). Pearson correlation coefficient is shown. Data were obtained from 12 different individuals and each point represents 1 individual.