Pregnancy Protects the Unborn from Immune Attacks

first_img(Visited 37 times, 1 visits today)FacebookTwitterPinterestSave分享0 The mother’s immune system learns how to protect the embryo instead of attacking it as foreign material.The immune system is blind; it has no brain on its own.  It is programmed to identify and fight foreign substances; that it does very well.  How, then, can it identify a firstborn implanted embryo as a feature that needs protection instead of attack?  The embryo contains antigens from the father, and its own unique genetic blend, that should rouse the mother’s immune system to fight it as an invader.Specific proteins in specific immune cells are there to help.  They “learn” that pregnancy is a good thing, and they remember it when the next baby is on the way.  A paper in Nature described new findings about this elaborate process.Pregnancy is an intricately orchestrated process where immune effector cells with fetal specificity are selectively silenced. This requires the sustained expansion of immune-suppressive maternal FOXP3+ regulatory T cells (Treg cells), because even transient partial ablation triggers fetal-specific effector T-cell activation and pregnancy loss. …. Here we show that pregnancy selectively stimulates the accumulation of maternal FOXP3+ CD4 cells with fetal specificity using tetramer-based enrichment that allows the identification of rare endogenous T cells. Interestingly, after delivery, fetal-specific Treg cells persist at elevated levels, maintain tolerance to pre-existing fetal antigen, and rapidly re-accumulate during subsequent pregnancy…. Thus, pregnancy imprints FOXP3+ CD4 cells that sustain protective regulatory memory to fetal antigen.   (Rowe et al., “Pregnancy imprints regulatory memory that sustains anergy to fetal antigen,” Nature 490, 4 Oct 2012, pp. 102–106, doi:10.1038/nature11462.)In the same issue of Nature, Alexander G. Betz described the challenge a mother’s immune system faces:Pregnancy poses a conundrum for the immune systems of placental mammals. A pregnant female’s immune system has to defend both mother and fetus from pathogens, while at the same time tolerating the fetus, which contains antigens that the maternal immune system recognizes as foreign because they are the products of genes inherited from the father. On page 102 of this issue, Rowe et al. demonstrate that, during pregnancy, immune cells called regulatory T cells that recognize these paternal antigens proliferate in the mother and specifically suppress the maternal immune response against the fetus. Furthermore, the authors show that a pool of these cells remains long after delivery, facilitating tolerance in subsequent pregnancies.  (Alexander G. Betz, “Immunology: Tolerating pregnancy,” Nature 490, 4 Oct 2012, pp. 47–48, doi:10.1038/490047a.)How did this protective system evolve?  Rowe et al. did not discuss evolution at all, but Betz offered his opinions:Genetically, a fetus is half mother, half father. From an evolutionary perspective, maternal exposure to paternal antigens in the fetus is a relatively new problem: most animals lay eggs, so tolerance is not an issue. Yet physical attachment of the developing mammalian fetus to the mother’s uterine wall by the placenta provides clear benefits — it allows gas exchange, nutrient uptake and waste disposal through the mother’s blood circulation, providing optimal conditions for the growth of the developing fetus. A systemic immune suppression to facilitate this fetal ‘implantation’ would be much too risky because it would expose the mother and developing offspring to infection. So placental animals had to evolve a mechanism for localized and specific immune suppression.One wonders how many babies had to die before evolution came up with this “mechanism,” this “intricately orchestrated process,” by chance.Over and over again we see evolutionists wasting time with stupid notions that are contrary to their own principles.  Evolution does not, and cannot, evolve something “for” something.  Evolution has no foresight, remember?  If it does anything, it recklessly damages what exists, with no care in the world, and then goes on to damage something else with chance mutations.  Whatever remains is that which was lucky enough not to die.  How many millions of embryos had to die for the Darwin lottery to keep the embryo from being destroyed by the immune system?If that were evolution’s only challenge, it would be one thing.  But pregnancy is a part of a hugely complex, interconnected system (“intricately orchestrated process”) involving three individuals: father, mother, and child.  Betz was wrong to say, “Genetically, a fetus is half mother, half father.”  No–a fetus (for humans, a baby) is its own individual being, different from both parents even though related.  If Betz were right, every child would be identical.  We all know that each baby is unique in the universe despite inheriting some clear similarities from both father and mother.  There’s no one else like you; no one else has an identical genetic makeup.How did an egg-laying animal develop a uterus in which the embryo would implant itself in the first place?  Egg laying is very different from pregnancy.  One only has to watch the documentaries on fertilization, implantation, development, and childbirth to get just a fragment of a glimpse into the numerous matching systems that all have to work perfectly together, right on time (example: David Menton’s lecture on YouTube).  Most are matters of life and death.  For instance, after relying on its mother’s placenta for 9 months, a newborn baby has to switch on its own independent breathing, with the heart sending to the lungs and liver, or it will die.  In your wildest imagination, suppose evolution got it to that point, but failed to find the lucky mutation to say, “Baby, breathe!”  How many trillions of babies died waiting for the thousands of beneficial mutations to “happen” that Darwinism requires?  Good grief; you get the point.Betz’s speculations about what mechanisms evolution came up with “for” surviving pregnancy add nothing but baloney to a great scientific paper that was doing just fine till Betz felt his inner compulsion to offer sacrifice to Charlie.  Maybe Nature asked him to do it so intelligent design would not be so obvious an inference.last_img

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