Perturbation of the natural killer cell compartment during primary human immunodeficiency virus 1 infection primarily involving the CD56 bright subset

Abstract

We investigated the distribution of natural killer (NK) cell subsets, their activating and inhibitory receptors, and their cytolytic potential, in primary human immunodeficiency virus (HIV)-infected (PHI) individuals at baseline and during 1 year of follow-up with or without antiretroviral therapy, and compared the results with those obtained in treatment-naïve, chronically HIV-infected (CHI) individuals, and HIV-seronegative (HN) healthy individuals. The proportion of the CD56(dim) and CD56(bright) subsets decreased with disease progression, whereas that of the CD56(-) CD16(+) subset increased. In the CD56(dim) subset, the proportion of cells with natural cytotoxicity receptors (NCRs) decreased with disease progression, and their cytolytic potential was reduced. Conversely, the CD56(bright) subset was characterized by a high proportion of NCR-positive, killer cell immunoglobulin-like receptor (KIR)-positive NKG2A(+) cells in both CHI and PHI individuals, which was associated with an increase in their cytolytic potential. During the 1 year of follow-up, the PHI individuals with high viraemia levels and low CD4(+) T-cell counts who received highly active antiretroviral therapy (HAART) had a similar proportion of NK subsets to CHI individuals, while patients with low viraemia levels and high CD4(+) T-cell counts who remained untreated had values similar to those of the HN individuals. Our results indicate a marked perturbation of the NK cell compartment during HIV-1 infection that is multifaceted, starts early and is progressive, primarily involves the CD56(bright) subset, and is partially corrected by effective HAART.

Figure 1

Representative dot plots of the expression of surface receptors on natural killer (NK) cells. Peripheral blood mononuclear cells were stained with anti-CD3-fluorescein isothiocyanate (FITC), anti-CD56-phycoerythrin-cyanin-5 (PC5), and a series of phycoerythrin (PE)-conjugated anti-NK cell receptor monoclonal antibodies (mAbs). Based on forward and side scatter analysis, we first gated on lymphocytes (not shown) and then on CD3⁻ cells (a), and the expression of the different NK cell receptors in the CD56^dim or CD56^bright subsets was analysed (b–f).

Figure 2

Representative dot plots of CD107a expression on CD56^dim and CD56^bright natural killer (NK) cell subsets. Interleukin (IL)-2-stimulated peripheral blood mononuclear cells were cultured in medium alone or with the K562 or P185 cell line in the presence of an irrelevant monoclonal antibody (mAb) (MOV10) or anti-(α-)activating NK-receptor mAbs (NKp46, NKp30, NKp44 and NKG2D), and stained with anti-CD3-fluorescein isothiocyanate (FITC), anti-CD56-phycoerythrin-cyanin-5 (PC5) and anti-CD107a-phycoerythrin (PE) mAbs. After gating on lymphocytes (not shown), the CD3⁺ cells were excluded from the analysis, and the percentage of CD107a⁺ cells in the CD56^dim and CD56^bright subsets was determined.

Figure 3

Frequency of CD56^dim and CD56^bright subsets in CD3⁻ CD56⁺ blood natural killer (NK) cells. (a, b) Proportion of CD56^dim and CD56^bright subsets among the CD3⁻ CD56⁺ NK cells analysed in (a) chronic HIV-infected (CHI) individuals, primary HIV-infected (PHI) individuals and HIV-negative (HN) healthy individuals, and in (b) PHI individuals treated with highly active antiretroviral therapy (HAART) and not treated with HAART (No HAART) at baseline (T0) and during follow-up at weeks 4, 24 and 48 (w4, w24 and w48, respectively). (c) Surface density of NKp46 and NKG2D molecules, expressed as mean fluorescence intensity (MFI), in the three groups, and in the treated (HAART) and untreated (No HAART) PHI individuals at baseline (T0) and during follow-up (w4, w24 and w48). Data are expressed as median values, with 25th and 75th percentiles.

Figure 4

Frequency of NKp30⁺, NKp46⁺, NKp44⁺ and NKG2D⁺ cells in CD56^dim and CD56^bright blood natural killer (NK) cell subsets. Gating on CD3⁻ CD56^dim or CD3⁻ CD56^bright NK subsets, we analysed the proportion of CD56^dim cells (a and b, top) or CD56^bright cells (a and b, bottom) showing the surface expression of NKp30, NKp46, NKp44 or NKG2D receptors. (a) Chronic HIV-infected (CHI) individuals, primary HIV-infected (PHI) individuals and HIV-negative (HN) healthy individuals. (b) PHI individuals treated with highly active antiretroviral therapy (HAART) and not treated with HAART (No HAART) at baseline (T0) and during follow-up at weeks 4, 24 and 48 (w4, w24 and w48, respectively). Data are expressed as median values, with 25th and 75th percentiles.

Figure 5

Frequency of killer cell immunoglobulin-like receptor-positive (KIR⁺) or NKG2A⁺ cells in CD56^dim and CD56^bright blood natural killer (NK) cell subsets. Gating on CD3⁻ CD56^dim or CD3⁻ CD56^bright NK cell subsets, we analysed the proportion of CD56^dim cells (top) or CD56^bright cells (bottom) showing CD158b, CD158e and CD158i KIRs, or NKG2A receptors in chronic HIV-infected (CHI) individuals, primary HIV-infected (PHI) individuals and HIV-negative (HN) healthy individuals. Data are expressed as median values, with 25th and 75th percentiles.

Figure 6

Functional capacity of natural killer (NK) cell subsets. Expression of CD107a on CD56^dim (a and b, top) and CD56^bright (a and b, bottom) NK cell subsets after co-culturing interleukin (IL)-2-stimulated peripheral blood mononuclear cells with the K562 cell-line or the P185 cell-line in the presence or absence of anti-NKp46, anti-NKp30, anti-NKp44 or anti-NKG2D monoclonal antibodies (mAbs) was determined. (a) Chronic HIV-infected (CHI) individuals (n = 4), primary HIV-infected (PHI) individuals (n = 7), and HIV-negative (HN) healthy individuals (n = 8). (b) PHI individuals treated with highly active antiretroviral therapy (HAART; n = 4) and not treated with HAART (No HAART; n = 3) at baseline. Data are expressed as mean values plus standard deviation. (c) Percentage of CD56^bright NK cells expressing CD107a molecules in four representative PHI individuals treated with HAART (HAART) or untreated (No HAART) at baseline and after 48 weeks of follow-up. IL-2-stimulated peripheral blood mononuclear cells were co-cultured with the P815 cell line in the presence of anti-NKp46 (black), anti-NKG2D (grey), anti-NKp30 (white) or anti-NKp44 (hatched) mAbs.