Impact of HIV on CD8+ T Cell CD57 Expression Is Distinct from That of CMV and Aging

Background: Chronic antigenic stimulation by cytomegalovirus (CMV) is thought to increase ‘‘immunosenesence’’ of aging, characterized by accumulation of terminally differentiated CD28- CD8+ T cells and increased CD57, a marker of proliferative history. Whether chronic HIV infection causes similar effects is currently unclear. Methods: We compared markers of CD8+ T cell differentiation (e.g., CD28, CD27, CCR7, CD45RA) and CD57 expression on CD28- CD8+ T cells in healthy HIV-uninfected adults with and without CMV infection and in both untreated and antiretroviral therapy (ART)-suppressed HIV-infected adults with asymptomatic CMV infection. Results: Compared to HIV-uninfected adults without CMV (n = 12), those with asymptomatic CMV infection (n = 31) had a higher proportion of CD28-CD8+ T cells expressing CD57 (P = 0.005). Older age was also associated with greater proportions of CD28-CD8+ T cells expressing CD57 (rho: 0.47, P = 0.007). In contrast, untreated HIV-infected CMV+ participants (n = 55) had much lower proportions of CD28- CD8+ cells expressing CD57 than HIV-uninfected CMV+ participants (P,0.0001) and were enriched for less well-differentiated CD28- transitional memory (TTR) CD8+ T cells (P,0.0001). Chronically HIV-infected adults maintaining ART-mediated viral suppression (n = 96) had higher proportions of CD28-CD8+ T cells expressing CD57 than untreated patients (P,0.0001), but continued to have significantly lower levels than HIV-uninfected controls (P = 0.001). Among 45 HIV-infected individuals initiating their first ART regimen, the proportion of CD28-CD8+ T cells expressing CD57 declined (P,0.0001), which correlated with a decline in percent of transitional memory CD8+ T cells, and appeared to be largely explained by a decline in CD28-CD57- CD8+ T cell counts rather than an expansion of CD28-CD57+ CD8+ T cell counts. Conclusions: Unlike CMV and aging, which are associated with terminal differentiation and proliferation of effector memory CD8+ T cells, HIV inhibits this process, expanding less well-differentiated CD28- CD8+ T cells and decreasing the proportion of CD28- CD8+ T cells that express CD57

The immunological footprint of CMV in HIV-1 patients stable on long-term ART

BACKGROUND:Most HIV-infected persons are cytomegalovirus (CMV) seropositive and retain latent virus that can be reactivated by immune activation. Their T cell populations express markers reflecting a late stage of differentiation, but the contributions of HIV and CMV to this profile are unclear. We investigated the immunological "footprint" of CMV in HIV patients who had a history of extreme immunodeficiency but were now stable on antiretroviral therapy (ART).RESULTS:Twenty CMV seropositive HIV patients >50years old with nadir CD4 T-cell counts <200 cells/mul were studied after >12years on ART. 16 CMV seropositive and 9 CMV seronegative healthy controls were included. CMV antibody titres were higher in HIV patients than controls (P<0.001-0.003). Levels of soluble B-cell activating factor (sBAFF) were elevated in patients (P=0.002) and correlated with levels of CMV antibodies (P=0.03-0.002), with no clear relationship in controls. CD8 T-cell IFNgamma responses to the IE1 peptide (VLE) remained elevated in HIV patients (P=0.005). The CD57 + CD45RA + CD27 phenotype of CD8 T-cells correlated with age (r=0.60, P=0.006), antibodies against CMV IE1 protein (r=0.44, P=0.06) and CD4 T-cell IFNgamma response to CMV lysate (r=0.45, P=0.05).CONCLUSIONS:Humoral and T-cell responses to CMV remained elevated in HIV patients after >12years on ART. Age and presence of CMV disease influenced CD8 T-cell phenotypes. Elevated levels of sBAFF may be a consequence of HIV disease and contribute to high titres of CMV antibody