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Volume 6 Supplement 3

AIDS Vaccine 2009

P02-07. High concentrations of interleukin-15 and low concentrations of CCL5 in breast milk are associated with protection against postnatal HIV transmission

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Natural variations in IL-15 concentration have not been investigated for an association with an immune-protection against HIV. Given IL-15's central role in anti-HIV immunity, we hypothesized that higher concentrations of IL-15 in breast milk may protect against postnatal mother-to-child HIV transmission.


In a case-control study nested within a clinical trial in Zambia, we compared IL-15 concentrations in breast milk of 22 HIV-infected women who transmitted HIV to their infants through breastfeeding with those of 72 who did not, as well as 18 HIV-uninfected women. Breast milk HIV RNA quantity, sodium, CXCL12, CCL5, and IL-8 concentrations were measured as well as maternal plasma HIV RNA concentrations and CD4 cell count. We used logistic regression modeling to adjust for potential confounders.


Higher concentrations of IL-15 in breast milk (adjusted odds ratio [AOR]: 0.01 per log10 pg/ml increase, 95% confidence interval [CI]: <0.001 to 0.3) were associated with protection against postnatal HIV transmission in univariate analysis and after adjusting for maternal CD4 cell counts, breast milk HIV RNA, CCL5, CXCL12, and IL-8 concentrations. Breast milk IL-15 concentration correlated with breast milk sodium, the other cytokines and HIV RNA concentration. It was inversely correlated with infant birth weight and tended to be higher in 1 week than in 1 month post-partum samples. Breast milk CCL5 concentrations were associated with increased risk of HIV transmission (AOR: 12.7 95% CI: 1.6 to 102.0) in adjusted analysis. Breast milk CXCL12 and IL-8 concentrations were not independently associated with transmission.


High concentration of IL-15 were associated with a protection against breastfeeding HIV transmission after adjusting for other pro-inflammatory cytokines, HIV RNA in breast milk, and maternal CD4 cell count. These results corroborate a protective role of IL-15-mediated cellular immunity against HIV transmission during breastfeeding. They are informative for vaccination studies using IL-15 as an adjuvant.

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Correspondence to J Walter.

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Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution 2.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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  • Breast Milk
  • Maternal Plasma
  • Infant Birth
  • CCL5 Concentration
  • Milk Sodium