The impact of maternal HIV infection on cord blood lymphocyte subsets and cytokine profile in exposed non-infected newborns

Abstract

Background: Children born to HIV+ mothers are exposed intra-utero to several drugs and cytokines that can modify the developing immune system, and influence the newborn's immune response to infections and vaccines. We analyzed the relation between the distribution of cord blood lymphocyte subsets and cytokine profile in term newborns of HIV+ mothers using HAART during pregnancy and compared them to normal newborns.

Methods: In a prospective, controlled study, 36 mother-child pairs from HIV+ mothers and 15 HIV-uninfected mothers were studied. Hematological features and cytokine profiles of mothers at 35 weeks of pregnancy were examined. Maternal and cord lymphocyte subsets as well as B-cell maturation in cord blood were analyzed by flow cytometry. The non-stimulated, as well as BCG- and PHA-stimulated production of IL2, IL4, IL7, IL10, IL12, IFN-γ and TNF-alpha in mononuclear cell cultures from mothers and infants were quantified using ELISA.

Results: After one year follow-up none of the exposed infants became seropositive for HIV. An increase in B lymphocytes, especially the CD19/CD5+ ones, was observed in cord blood of HIV-exposed newborns. Children of HIV+ hard drug using mothers had also an increase of immature B-cells. Cord blood mononuclear cells of HIV-exposed newborns produced less IL-4 and IL-7 and more IL-10 and IFN-γ in culture than those of uninfected mothers. Cytokine values in supernatants were similar in infants and their mothers except for IFN-γ and TNF-alpha that were higher in HIV+ mothers, especially in drug abusing ones. Cord blood CD19/CD5+ lymphocytes showed a positive correlation with cord IL-7 and IL-10. A higher maternal age and smoking was associated with a decrease of cord blood CD4+ cells.

Conclusions: in uninfected infants born to HIV+ women, several immunological abnormalities were found, related to the residual maternal immune changes induced by the HIV infection and those associated with antiretroviral treatment. Maternal smoking was associated to changes in cord CD3/CD4 lymphocytes and maternal hard drug abuse was associated with more pronounced changes in the cord B cell line.

Figure 1

Analysis of B-cell maturation in cord blood of a normal newborn (control group). Expression of CD34 was used to identify immature B-cells. Maturation was studied using the expression of CD45, CD22, CD10 and membrane IgM (sIgM). A) CD45/CD34/CD19/CD22 combination - black: immature cells - CD45^lowCD34⁺CD19⁺CD22^- red: intermediate cells - CD45^-/+CD34^lowCD19⁺CD22⁺ yellow: mature cells - CD45⁺CD34^-CD19⁺CD22⁺. B) sIgM/CD34/CD19/CD10 combination - black: immature cells - sIgM^-CD34⁺CD19⁺CD10^-/+ red: intermediate cells - sIgM⁺CD34^-/+CD19⁺CD10^-/+ yellow: mature cells - sIgM⁺CD34^-CD19⁺CD10^-/+.

Figure 2

Analysis of T cell proliferation of non-stimulated (A) and PHA-stimulated (B) cord mononuclear cells of a newborn from a HIV-infected mother. After gating of CD3 cells, events were analyzed for size and complexity (forward-scatter and side-scatter gates), from which resting (R1-green) and blast cells (R2-blue) were separated. T-lymphocyte subsets were then analyzed. Dead cells (red) were excluded from all analyses. T cell proliferation was the difference between the percentages of PHA-stimulated blasts and non-stimulated blasts.