Human immunodeficiency virus (HIV) infection during pregnancy induces CD4 T-cell differentiation and modulates responses to Bacille Calmette-Guérin (BCG) vaccine in HIV-uninfected infants

Abstract

Human immunodeficiency virus (HIV)-negative infants born to HIV-positive mothers frequently exhibit a range of immunological abnormalities. We tested the hypothesis that HIV during pregnancy affects the ability of CD4 T cells of HIV-negative infants to respond to vaccine challenge by recruiting HIV-negative infants born to HIV-negative and HIV-positive mothers and measuring their responses to Bacille Calmette-Guérin (BCG) vaccine given at birth. At 2 weeks, maternal HIV status did not influence CD4 T-cell counts or differentiation, but by 10 weeks CD4 counts of infants born to HIV-positive mothers fell to a level characteristic of HIV-positive infants. Among the CD4 T-cell populations, markers of differentiation (CCR7(-) CD45RA(-) CD27(-)) and senescence (CD57, PD-1) were more common among infants born to HIV-positive mothers than among infants born to HIV-negative mothers. At 2 weeks of age, we assessed the effector response to heat-killed BCG and tuberculin purified protein derivative (PPD) by overnight interferon (IFN)-gamma enzyme-linked immunosorbent spot-forming cell assay (ELISpot), but found no measurable effect of maternal HIV status. At 10 weeks, we assessed CD4 T-cell memory by measuring proliferation in response to the same antigens. We observed a bimodal response that allowed infants to be classified as high or low responders and found that fewer infants born to HIV-positive mothers were able to mount a robust proliferative response, suggesting that their reduced CD4 counts and increased differentiation indicated a deficiency in their ability to develop immunological memory.

Figure 1

Maternal human immunodeficiency virus (HIV) infection increases CD4 T-cell differentiation in 10-week-old HIV-negative infants. (a) CD45RA and CCR7 expression in representative 10-week-old HIV-negative infants with HIV-positive and HIV-negative mothers, gated on CD4 T cells. (b) Concentrations of CD4 T-cell subpopulations defined by CD45RA and CCR7 in 2- and 10-week-old infants with HIV-positive and HIV-negative mothers. (c) CD27 and CD28 expression in representative 10-week-old HIV-negative infants with HIV-positive and HIV-negative mothers, gated on CD4 T cells. (d) Concentrations of CD4 T-cell subpopulations defined by CD27 and CD28 in 2- and 10-week-old infants with HIV-positive and HIV-negative mothers. On composite plots, grey bars indicate medians. All statistical analysis was performed using the Mann–Whitney U-test.

Figure 2

Maternal human immunodeficiency virus (HIV) infection leads to a higher proportion of CD4 T cells expressing markers of senescence in 10-week-old HIV-negative infants. (a) Representative CD57 and CD27 expression by CD4 T cells of 10-week-old HIV-negative infants with HIV-positive and HIV-negative mothers. Percentages of CD4 T cells expressing CD57 are given. (b) Percentage of CD4 T cells expressing CD57 at 2 and 10 weeks of age in HIV-negative infants born to HIV-negative and HIV-positive mothers. Bars indicate medians. (c) PD-1 and CD27 expression by the CD4 T-cells of HIV-negative infants with HIV-positive and HIV-negative mothers. Percentages of total CD4 T cells expressing PD-1 are given. (d) Percentage of CD4 T cells expressing PD-1 at 2 and 10 weeks of age in HIV-negative infants born to HIV-negative and HIV-positive mothers. Bars indicate medians. All statistical comparisons were by Mann–Whitney U-test.

Figure 3

Maternal human immunodeficiency virus (HIV) status has no discernable effect on interferon (IFN)-γ release in 2-week-old infants. The peripheral blood mononuclear cells (PBMCs) of 2-week-old infants were stimulated with (a) heat-killed Bacille Calmette-Guérin (BCG) or (b) purified protein derivative (PPD) and IFN-γ responses measured by enzyme-linked immunosorbent spot-forming cell assay (ELISpot) after 18 hr. Values are expressed as negative control subtracted from treatment, so cases where proliferation was greater in the negative control return negative values.

Figure 4

Maternal human immunodeficiency virus (HIV) infection leads to a reduced antigen-specific proliferation in 10-week-old HIV-negative infants. Plots indicate percentages of divided CD4 T cells, measured by carboxyfluorescein diacetate succinimidyl ester (CFSE) dilution, following 8 days of culture after stimulation with (a) purified protein derivative (PPD) and (b) Bacille Calmette-Guérin (BCG), and percentages of divided CD8 T cells after stimulation with (c) PPD and (d) BCG. The dashed line indicates delineation of high-level responders. Values are expressed as negative control subtracted from treatment, so cases where proliferation was greater in the negative control return negative values.