[pronut-hiv] Breast Milk Defensins May Help Prevent Vertical HIV Transmission

["ProNut-HIV" <pronut-hiv@healthnet.org>]

Breast Milk Defensins May Help Prevent Vertical HIV Transmission
By Megan Rauscher

NEW YORK (Reuters Health) Jul 01 - Alpha-defensin, an innate immune
factor with documented anti-HIV activity, appears to play a role in the
prevention of HIV transmission among breastfed infants, according to a
report in the June 1st Journal of Acquired Immune Deficiency Syndromes.

In a nested case-control study of HIV-infected Zambian mothers who
breastfed their infants, alpha-defensin concentrations were markedly
higher among the 32 mothers who did not transmit HIV to their infants
compared to the 52 whose infants did become HIV positive.

"Alpha-defensins appear to be another anti-infective factor present in
human milk, among the many other immunologically-active components of
breast milk, that augment the newborn's immune defenses," Dr. Louise
Kuhn from Columbia University in New York told Reuters Health.

Alpha-defensins have been detected in breast milk, but their role in
mother-to-child HIV transmission has not been studied until now.

Dr. Kuhn's team detected alpha-defensins in 79% of breast milk samples
tested. Concentrations of this peptide, they report, increased as breast
milk HIV RNA quantity increased. Also, breast milk HIV RNA quantity was
a "strong and significant predictor" of HIV transmission.

However, after adjustment for milk HIV RNA quantity, a high
alpha-defensin concentration significantly reduced the risk of
intrapartum and postnatal HIV transmission (odds ratio = 0.3).

Alpha-defensins in breast milk "may help explain why transmission
through this route is relatively inefficient, despite the prolonged and
extensive exposure of breastfed infants to virus," Dr. Kuhn said.

"However, since much remains unknown about the processes involved," she
added, "including why one mother produces high levels of alpha-defensin
in her breast milk and another does not, counselors of HIV-positive
mothers should continue to offer mothers information about the risks and
benefits of infant feeding options appropriate to their circumstances
and based on the availability or not of safer alternatives."

The results of the current study are consistent with prior studies that
have documented high alpha-defensin levels in HIV-infected long-term
non-progressors as well as in HIV-exposed uninfected individuals.

J Acquir Immune Defic Syndr 2005;39:138-142.