The role of transplacental microtransfusions of maternal lymphocytes in in utero HIV transmission.
BACKGROUND
The mechanisms of HIV transmission from mothers to infants are poorly understood. A possible mechanism of in utero transmission is transplacental transfer of HIV-infected maternal leukocytes into the fetal circulation during pregnancy.


OBJECTIVE
To determine if the frequency of in utero HIV infection correlates with presence or levels of maternal cells (MCs) in placenta-derived cord blood.


METHODS
DNA was extracted from dried cord blood spots (DBS) from newborns born to HIV+ mothers and corresponding maternal DBS specimens. Paired mother-infant samples were probed to identify unique maternal sequences targeted by 24 allele-specific real-time polymerase chain reaction assays. Infant DBS-derived DNA was then probed in replicate analyses for noninherited maternal allelic sequences. Rates of detection and levels of MCs in DBS samples of HIV(+) and HIV(-) newborns were compared.


RESULTS
Of 114 mother-infant pairs with informative alleles, 38 newborns were HIV(+) and 76 HIV(-), based on detection of HIV DNA/RNA at birth. MC were detected in 23 of 38 HIV(+) newborns (60.5%) and in 47 of 76 HIV(-) newborns (61.8%). The mean and median concentrations of nucleated MCs in DBS for the HIV(+)/MC(+) newborns (n = 23) were 0.33% and 0.27%, respectively, compared with 0.09% and 0.10% for the HIV(-)/MC(+) newborns (n = 47) (2-sample T test for means: P = 0.78).


CONCLUSIONS
There was no significant difference in rates of detection or concentrations of MC in DBS between HIV(+) and HIV(-) newborns. Therefore, we could not demonstrate a correlation between MC in DBS, assumed to reflect levels of in utero maternal-fetal cell trafficking, and the risk of in utero HIV transmission.
Lee
Tzong-Hae
TH
Blood Systems Research Institute, San Francisco, CA, USA.
Chafets
Daniel M
DM
Biggar
Robert J
RJ
McCune
Joseph M
JM
Busch
Michael P
MP
D005260:Female; D005312:Fetal Blood / Q000821:virology; D015658:HIV Infections / Q000635:transmission*; D006801:Humans; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000821:virology; D018445:Infectious Disease Transmission, Vertical; D008214:Lymphocytes / Q000821:virology*; D008431:Maternal-Fetal Exchange / Q000276:immunology*; D010920:Placenta / Q000276:immunology; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000276:immunology / Q000821:virology; D020133:Reverse Transcriptase Polymerase Chain Reaction