"MAMU AG" MAY BE KEY TO SUCCESSFUL PREGNANCY

How is the fetus protected from immune rejection by the mother, since half 
of its genes have been
inherited from the father?

This has long been a key question asked by reproductive and developmental 
biologists . Now, researchers at the Wisconsin Regional Primate Research 
Center are closing in on the answer.

According to new research from the lab of Ted Golos, Ph.D., the presence of 
specialized molecules on the surface of rhesus monkey placental cells at 
the time of implantation provides evidence of an important role for MHC 
class I molecules in the establishment of a successful pregnancy.

Golos, Igor Slukvin, Ph.D., David Watkins, Ph.D., and others identified 
Mamu-AG as a unique MHC class I molecule (a type of transplantation 
antigen) that shares many characteristics of a human placental molecule 
known as HLA-G.

"The true function of the human molecule remains unknown because of the 
inability to test hypotheses experimentally in women," Golos explains. "So 
the monkey is an invaluable model to examine the importance of this 
molecule in establishing and maintaining pregnancy."

Since the Mamu AG molecule is hypothesized to modulate the maternal immune 
system, additional potential significance may be in transplant biology. 
"There is interest in HLA-G in the context of organ transplantation," Golos 
says.

Scientists cannot study the interactions of the maternal immune system with 
the placenta without using pregnant animals. "We are using the rhesus 
monkey because its immune system and MHC molecules and most 
importantly,  the structure and function of its placenta are very similar 
to that in humans," Golos says.

The nonhuman primate model also allows researchers to look at the very 
earliest time during pregnancy, the implantation stage, when the most 
critical events for the establishment of pregnancy are occurring.

"This is the time when most embryonic loss occurs in humans, yet this very 
early time in pregnancy cannot be directly studied with human clinical 
samples."

Reference:
Slukvin, II, Lunn, DP, Watkins, DI, Golos, TG. 2000. Placental Expression 
of the nonclassical MHC class I molecule Mamu-AG at implantation in the 
rhesus monkey. PNAS 97(16): 9104-9.

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Primate-Science Research Highlights appears every other week and focuses
broadly on research involving non-human primates. Coverage includes
biomedicine, behavior, conservation and veterinary science. Please
submit highlights for this column to Larry Jacobsen, Primate-Science Research
Highlights editor, at jacobsen@primate.wisc.edu. A 300-word limit and
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supported by a grant from the National Institutes of Health,
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Wisconsin Regional Primate Research Center. No portion of this highlight
may be copied or redistributed without the consent of the editor.

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