CD57 has been described as a marker for replicative senescence, and its expression has been associated with shorter telomeres and diminished proliferative capacities on T and NK cells (4)

CD57 has been described as a marker for replicative senescence, and its expression has been associated with shorter telomeres and diminished proliferative capacities on T and NK cells (4). reside and circulate in peripheral sites (13). Mature NK cells are characterized by granules which harbor granzymes and perforin. These Rabbit polyclonal to ABCA3 NK cells are fully armed, ready-to-go effector cells (17). A number of NK cell abnormalities have been reported in HIV contamination (9), including high activation status (2,10), increased turnover (16), differential expression of activating and inhibitory receptors (20), impaired conversation with dendritic cells (12), and loss of CD56dimCD16+NK cells (23). CD56dimCD16+NK cells represent the largest NK cell subset in peripheral blood in healthy individuals. The expression of killer immunoglobulin-like receptors (KIRs) and CD57 are predominant features of this subpopulation (8,15). CD57 expression on NK cells Disopyramide has been Disopyramide previously associated with replicative senescence on T and NK cells (4), raising the question of how HIV-1 contamination alters CD57 expression on CD56dimCD16+NK cells. To the best of our knowledge, no one has addressed the phenotypic and functional properties of CD56dimCD16+NK cells that are preferentially lost during HIV contamination. Here, we provide evidence that increasing CD57 expression indicates terminal differentiation in healthy individuals, as well in as HIV-infected subjects. We furthermore show that HIV contamination is associated with preferential loss of less-differentiated cells, which are characterized by high activation status and turnover. In this study, blood samples from 37 HIV-seropositive individuals and 15 healthy subjects were analyzed; all HIV-infected patients were either antiretroviral therapy nave or untreated for more than one year. The HIV-positive study cohort comprised 10 patients with a viral load of less than 2,000 copies/ml, 14 patients with a viral load ranging from 2,000/ml to 20,000 copies/ml, and 13 patients with a viral load above 20,000 copies/ml. CD4 T cell counts ranged from 180/l to 1 1,355/l, the average being 457.3/l. The study was approved by the local ethics commission rate (Ethikkommission der Medizinischen Hochschule Hannover, Votum No. 3150), and all study participants gave informed written consent for their participation. Flow cytometric analysis was performed on cryopreserved peripheral blood mononuclear cells (PBMCs) as previously described (21,22). A list of monoclonal antibodies employed in this study is usually available upon request. For intracellular analysis of granzyme B, perforin, and Ki-67, we used a fixation and permeabilization kit (Invitrogen). At least 1 million events were acquired for each sample, using either a FACSAria or LSR II flow cytometer (BD Biosciences). Data were analyzed with FlowJo (TreeStar). Lymphocytes were defined by forward and side scatter. CD3+, CD14+, CD19+, dead cells, and cell aggregates were removed from analysis based on peridinin chlorophyll protein and Viaprobe staining and gating on a plot of forward-scatter area versus forward-scatter height (Fig.1A). NK cells and their distinctive subpopulations were defined based on their CD56 and/or CD16 expression. Fluorescence-minus-one (FMO) staining was used to determine threshold values for the expression of specific markers. == FIG. 1. == HIV infection is associated with loss of CD57and CD57dimbut not CD57brightCD56dimCD16+NK cells. (A) Representative gating scheme for identification of NK cells. NK cells were defined as CD3CD14CD19lymphocytes expressing either CD56 or CD16 or both. We divided CD56dimCD16+NK Disopyramide cells into three subsets based on their level of CD57 expression: CD57, CD57dim, and CD57brightcells. Numbers on FACS plots indicate frequency of gated population. SSC-A, side scatter area; FSC-A, forward scatter area; FSC-W, forward scatter width. (B) Comparison of percentages of the CD57, CD57dim, and CD57brightsubpopulations in control subjects (n= 14) and HIV-seropositive individuals (n= 34) on CD56dimCD16+NK cells.ns, not significant (P> 0.05); **,P< 0.01; ***,P< 0.001. (C) Frequencies of CD57, CD57dim, and CD57brightexpressing CD56dimCD16+NK cells in relation to total NK cells in control subjects (n= 14) and HIV-seropositive individuals (n= 34). (D) Mean frequency of CD56dimCD16+NK cells in 14 control individuals and in 34 HIV-infected people and the distribution of CD57, CD57dim, and CD57brightcells within CD56dimCD16+NK cells is shown..