Peripheral adenosine deaminase 1 activity is a biomarker for placental malaria and inflammation.
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Date
2006
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
American Journal of Obstetrics & Gynecology
Abstract
Objective
Placental malaria (PM) complicated by placental inflammation is associated with low birthweight (LBW) at delivery, and has been estimated to cause 75,000 to 200,000 infant deaths per year in sub-Saharan Africa. Peripheral blood smears detect parasitemia in only about half of women with PM, making diagnosis difficult. Our objective is to find a simple, inexpensive prenatal test that can detect PM and inflammation and thereby identify pregnant women who are at the highest risk for delivery of LBW infants.
Study design
Placental and peripheral blood samples were obtained from consenting women age 18-45 years who delivered in Muheza, Tanzania, an area of intense malaria transmission. Microscopy of placental blood and placental tissue sections was used to detect PM and inflammation in mothers delivering singleton infants. Quantitative reverse transcriptase PCR and immunostaining were performed for adenosine deaminase 1 (ADA1). Total ADA plasma activity was assessed using a colorimetric assay, and ADA isotyping was performed by the addition of an ADA1 inhibitor, EHNA.
Results
Placental ADA1 mRNA levels were elevated during infection and correlated with inflammation. By immunohistochemistry, ADA1 protein was demonstrated to be produced only in PM-positive placentas, in maternal polynuclear cells located in intervillous spaces. Plasma ADA activity was elevated in women with PM compared to those without (p<0.001), in women with PM and inflammation compared to those with PM only (p=0.002), and in mothers of LBW infants compared to mothers of normal birthweight infants (p=0.01). Isotyping indicated that ADA1 is the predominant plasma isotype of women with PM. We estimate that the cost of reagents to measure ADA1 is approximately $0.01 per test.
Conclusion
Plasma ADA1 activity is a simple and inexpensive test that may help to identify those women with PM who are at risk of LBW infants. Applied prenatally, this assay could allow more intensive anti-malarial treatment of women with inflammatory PM and thereby potentially improve outcomes for their infants.
Description
Keywords
Africa, Placental malaria, Plasma
Citation
Steele, D., Muehlenbachs, A., Fried, M., Mutabingwa, T. and Duffy, P., 2006. Peripheral adenosine deaminase 1 activity is a biomarker for placental malaria and inflammation. American Journal of Obstetrics & Gynecology, 195(6), p.S75.