Baseline demographic and clinical characteristics of the subjects
A total of 21 HIV/AIDS patients were enrolled from Beijing You'an Hospital, Capital Medical University. At baseline, the average age of subjects was 36.8 ±12.1 years (range, 23-64 years). The median plasma viral load of subjects was 148,141 copies/ml (interquartile range 1,294-1,157,417 copies/mL), and the median CD4+ T cell count was 230 cells/μl (interquartile range 46-349 cells/μl). The median CD8+ T cell count was 1053 cells/μl (interquartile range 382-1675). And most of the subjects were men who have sex with men (MSM).
Changes of CD8+ T cells, naïve, CM, EM and EMRA subsets
The gating strategy of CD8+ T cell populations was shown in figure . Longitudinal analyses of CD8+ T cells, naïve, CM, EM and EMRA subsets in patients with asymptomatic chronic HIV infection after ART were shown in figure . The major components of CD8+ cells were EM and EMRA subsets, which accounted for over 80 percent. Naïve and CM subsets only accounted for less than 20 percent.
Figure 1 The gating strategy of CD8+ T cell populations from a single representative subject. Lymphocytes were gated first. Then CD8+ cells were gated. Central memory (CM; CD45RA-CCR7+), naive (CD45RA + CCR7+), effector memory (EM; CD45RA-CCR7-), and terminally (more ...)
Figure 2 Percentage changes in absolute CD8+ T cells and each phenotypic subset during initial ART (weeks). (A-E) Percentage changes of CD8+ T cells, CD8 CM, CD8 EM and CD8 EMRA subsets respectively. (F) Mean percentage changes of CD8+ T cells, CD8 CM, CD8 EM (more ...)
The median of CD8+ T cells decreased from 1053 to 904 cells/μl after 12 weeks of ART. Among the four subsets of CD8+ cells, CD8+ EM and CD8+ EMRA subsets had the same change pattern with CD8+ T cells. The median of CD8+ EM subset decreased significantly from 627 to 520 cells/μl. Similarly, the median of CD8+ EMRA subset decreased significantly from 325 to 272 cells/μl.
The median of CD8+ naïve cells at baseline, week 2, 4, 8 and 12 was 79, 91, 99, 98, 102 cells/μl respectively. There were no significant differences among them. The median of CD8+ CM subset kept slowly rising, from 21 cells/μl at baseline to 43 cells/μl at week 12 after ART.
Activation of CD8+ cell subsets
We next investigated the effect of ART on T cell activation. HIV-infected individuals had higher T-cell activation in the blood as indicated by expression of HLA-DR and CD38 [9
]. Given the limited experimental conditions, we did not stain CD38 with HLA-DR simultaneously. At baseline the median proportion of activated CD8+ T lymphocytes (CD38+) exceeded 80% and gradually declined over 12 weeks, reaching 73.77% (73.77 ± 9.14) at the last follow up visit. Activation of CD8+ EM subsets decreased in a similar way, from 83.53% at baseline to 72.87% at week 12. The median of activation of CD8+ naïve cell subset was 62.997% at baseline. It fluctuated between 49.09% and 65.79%, reaching to 63.32% at week 12.
The median of percentage of CD38+ CD8+ CM subset was 57.81%, 55.63%, 52.82%, 54.49% and 50.18% respectively at the 5 times of follow up visits, fluctuating between 50% and 58%. The median of CD8+ EMRA subset was 84.43%, 86.11%, 83.64%, 85.22% and 83.90% respectively at the 5 times of follow up visits, staying at a high level. Activation levels of the two subsets had no significant changes after ART.
With respect to HLA-DR expression on CD8+ lymphocytes, there was also a high percentage of expression at base line. The percentage of HLA-DR expression decreased from 76.91% at baseline to 71.26 at week 12 after ART, which has the similar change pattern to that of CD38 expression.
The median of HLA-DR expression on CD8+ naïve cell subset declined from 9.39% at baseline to 7.24% at week 12 after ART. For CD8+ CM subset, the median percentage of HLA-DR expression declined from 65.91% at baseline to 51.43% at week 12. The median percentages of CD8+ EM and EMRA subsets were both in a high level around 80%. There were no significant changes in activation of CD8+ EM and EMRA subsets as indicated by HLA-DR.
Proliferation of CD8+ cell subsets
Proliferating subsets are calculated by measurement of Ki67 expression. The median of percentage of Ki67+CD8+ T cells elevated slightly at the first 4 weeks of ART, then decreased gradually. Their values at the 5 times of follow up visits were 4.85%, 7.27%, 6.85%, 5.73% and 4.27% respectively.
The median of proliferation of CD8+ naïve subset was 1.29%, 1.47%, 1.33%, 0.83% and 0.85% respectively at the 5 times of follow up visits. And the median of proliferation of CD8+ CM subset was 7.47%, 8.05%, 8.52%, 5.41% and 4.40% respectively. Both of the two subsets had the trend of decline.
Ki67 expression on CD8+ EM cells had no significantly change after ART, fluctuating between 5.60% and 9.65%. For CD8+ EMRA cells, percentage of Ki67 positive cells elevated after ART, reaching to peak of 4.09% at week 8, then decreased to 2.74% at week 12.
The changes of mean fluorescence index (MFI) of CD38 and Ki67 on CD8+ cell subsets have the same pattern with those of percentages (data not shown).