question: If a pregnant woman eats peanut butter and her fetus is severely allergic to peanuts, how does the fetus survive?
comment: the fetus does not have an independent immune system. if the mother is okay to eat it there is no problem. its the same reason why you shouldn't smoke or drink while pregnant. the Fetus is basically parasitic to the mothers systems and will more or less run the same as the mothers until it becomes an independent organism.
passages: Regulatory T cells also likely play a role.
  
  Also, a shift from cell-mediated immunity toward humoral immunity is believed to occur.
  
  Section::::Insufficient tolerance.
  
  Many cases of spontaneous abortion may be described in the same way as maternal transplant rejection, and a chronic insufficient tolerance may cause infertility. Other examples of insufficient immune tolerance in pregnancy are Rh disease and pre-eclampsia:
   BULLET::::- It secretes Neurokinin B containing phosphocholine molecules. This is the same mechanism used by parasitic nematodes to avoid detection by the immune system of their host.
  
  BULLET::::- Also, there is presence of small lymphocytic suppressor cells in the fetus that inhibit maternal cytotoxic T cells by inhibiting the response to interleukin 2.
   Within the first 2 days after birth, kittens acquire passive immunity from their mother’s milk. Milk within the first few days of parturition is called colostrum, and contains high concentrations of immunoglobulins. These include immunoglobulin A and immunoglobulin G which cross the intestinal barrier of the neonate. The immunoglobulins and growth factors found in the colostrum begin to establish and strengthen the weak immune system of the offspring. Kittens are able to chew solid food around 5–6 weeks after birth, and it is recommended that 30% of their diet should consist of solid food at this time. The kitten remains on the mother’s milk until around eight weeks of age when weaning is complete and a diet of solid food is the primary food source.
   Section::::Role of the placenta.
  
  The healthy placenta is a semipermeable membrane that does form a barrier for most pathogens and for certain xenobiotic substances. However, it is by design an imperfect barrier since it must transport substances required for growth and development. Placental transport can be by passive diffusion for smaller molecules that are lipid soluble or
   The cornerstone of the immune system is the recognition of "self" versus "non-self". Therefore, the mechanisms that protect the human fetus (which is considered "non-self") from attack by the immune system, are particularly interesting. Although no comprehensive explanation has emerged to explain this mysterious, and often repeated, lack of rejection, two classical reasons may explain how the fetus is tolerated. The first is that the fetus occupies a portion of the body protected by a non-immunological barrier, the uterus, which the immune system does not routinely patrol. The second is that the fetus itself may promote local immunosuppression in the mother, perhaps by a process of active nutrient depletion. A more modern explanation for this induction of tolerance is that specific glycoproteins expressed in the uterus during pregnancy suppress the uterine immune response (see eu-FEDS).
   There is conflicting evidence on whether maternal diet during pregnancy has any effect on development of allergies due to a lack of good studies. A 2010 systematic review of clinical research indicated that there is insufficient evidence for whether maternal peanut exposure, or early consumption of peanuts by children, affects sensitivity for peanut allergy.
  
  Section::::Cause.:Routes of exposure.
   Immune tolerance in pregnancy
  
  Immune tolerance in pregnancy or maternal immune tolerance is the immune tolerance shown towards the fetus and placenta during pregnancy. This tolerance counters the immune response that would normally result in the rejection of something foreign in the body, as can happen in cases of spontaneous abortion. It is studied within the field of reproductive immunology.
  
  Section::::Mechanisms.
  
  Section::::Mechanisms.:Placental mechanisms.
  
  The placenta functions as an immunological barrier between the mother and the fetus, creating an immunologically privileged site. For this purpose, it uses several mechanisms:
   The mother’s immune system is able to provide protection from microbial infections without mounting an immune response against fetal tissues expressing paternally inherited alloantigens. A better understanding of the immunology of pregnancy may lead to the discovery of reasons for miscarriage.
   Giving peanut products early may decrease the risk allergies while only breastfeeding during at least the first few months of life may decrease the risk of dermatitis. There is no good evidence that a mother's diet during pregnancy or breastfeeding affects the risk. Nor is there evidence that delayed introduction of certain foods is useful. Early exposure to potential allergens may actually be protective. 
  
  Fish oil supplementation during pregnancy is associated with a lower risk. Probiotic supplements during pregnancy or infancy may help to prevent atopic dermatitis.
  
  Section::::Management.
   Neonates with biliary atresia were found to have null GSTM1 genotype while all their moms were heterozygous for GSTM1. Thus these infants are protected intrauterine by their maternal detoxification system, yet once born they cannot handle the detoxification of aflatoxin load.
  
  Section::::Causes.:Toxins.
   Still, there is currently no drug that has evidence of preventing miscarriage by inhibition of maternal immune responses; aspirin has no effect in this case.
  
  Section::::Increased infectious susceptibility.
  
  The increased immune tolerance is believed to be a major contributing factor to an increased susceptibility and severity of infections in pregnancy. Pregnant women are more severely affected by, for example, influenza, hepatitis E, herpes simplex and malaria. The evidence is more limited for coccidioidomycosis, measles, smallpox, and varicella. However, pregnancy does not seem to alter the protective effects of vaccination.
  
  Section::::Interspecific pregnancy.
   Kittens without maternally derived antibodies are especially vulnerable. FPLV vaccination can start as early as 4 weeks of age for kitten at high risk, but are usually started at 6 weeks, then given every 3 – 4 weeks until 16 weeks of age. For cats older than 16 weeks, 2 doses, 3 to 4 weeks apart is generally recommended, followed by a 6-month to 1-year booster. Thereafter, a booster vaccination every 3 years is usually recommended; a blood titer test can be done to determine individual antibody levels for catering the timing of boosters.
  
  Section::::External links.
   Maternal IgG antibodies cross the placenta, giving the fetus passive immunity against those diseases for which the mother has antibodies. This transfer of antibodies in humans begins as early as the fifth month (gestational age) and certainly by the sixth month.
  
  Section::::Developmental problems.
   The fetus has a different genetic makeup than the mother, as it also translates its father's genes, and is thus perceived as foreign by the maternal immune system. Women who have borne multiple children by the same father typically have antibodies against the father's red blood cell and major histocompatibility complex (MHC) proteins. However, the fetus usually is not rejected by the mother, making it essentially a physiologically tolerated allograft. It is thought that the placental tissues which interface with maternal tissues not only try to escape immunological recognition by downregulating identifying MHC proteins but also actively induce a marked peripheral tolerance. Placental trophoblast cells express a unique Human Leukocyte Antigen (HLA-G) that inhibits attack by maternal NK cells. These cells also express IDO, which represses maternal T cell responses by amino acid starvation. Maternal T cells specific for paternal antigens are also suppressed by tolerogenic DCs and activated iTregs or cross-reacting nTregs. Some maternal Treg cells also release soluble fibrinogen-like proteins 2 (sFGL2), which suppresses the function of DCs and macrophages involved in inflammation and antigen presentation to reactive T cells These mechanisms altogether establish an immune-privileged state in the placenta that protects the fetus. A break in this peripheral tolerance results in miscarriage and fetal loss. (for more information, see Immune tolerance in pregnancy).
   BULLET::::- 2.) Linda's sister, Gayle, is staying with the Belchers for the holiday and she's bringing her pet cats. Bob, who's allergic to cats, begins taking allergy medication to combat his allergies.
   Section::::Prognosis.
  
  The mortality rate for THAN is relatively high unless immediate treatment is obtained. The duration of hyperammonemia is directly correlated to morbidity as well as the associated neurological conditions. After the first hyperammonemic episode, there is no increased risk for future hyperammonemic episodes, and normal protein consumption can be continued.
  
  Section::::Epidemiology.
   Section::::Physiological regulation.:Nutrition and diet.
  
  Overnutrition is associated with diseases such as diabetes and obesity, which are known to affect immune function. More moderate malnutrition, as well as certain specific trace mineral and nutrient deficiencies, can also compromise the immune response.
  
  Foods rich in certain fatty acids may foster a healthy immune system. Likewise, fetal undernourishment can cause a lifelong impairment of the immune system.
  
  Section::::Physiological regulation.:Repair and regeneration.
   Immunological responses could be the cause in many cases of infertility and miscarriage. Some immunological reasons that contribute to infertility are reproductive autoimmune failure syndrome, the presence of anti-phospholipid antibodies, and antinuclear antibodies.
   The damage threshold, or the initial nematode population density at which peanut yields begin to decline, has been reported to be in the range of 1 to 10 eggs and second stage juveniles per 500 cm3 soil for "M. arenaria" on susceptible peanut cultivars.
  
  Section::::Reproduction and life cycle.
   Active immune response against FPLV antibodies play an important role in the immune response to the virus. Maternally-derived antibodies (MDA) efficiently protect kittens from fatal infection. This passively acquired immunity is later replaced by an active immune response obtained by vaccination or as a consequence of a natural infection. In kittens, the period of greatest susceptibility to infection is when maternal antibodies are absent or waning and vaccine-induced immunity has not yet fully developed.
   BVDV infection between 80 and 150 days of gestation may be teratogenic, with the type of birth defect dependent upon the stage of fetal development at infection. Abortion may occur at any time during gestation. Infection after approximately day 120 can result in the birth of a normal fetus which is BVD antigen-negative and BVD antibody-positive. This occurs because the fetal immune system has developed, by this stage of gestation, and has the ability to recognise and fight off the invading virus, producing anti-BVD antibodies.
  
  Section::::Pathogenesis.:Chronic infections.
   by active transport for substances that are larger and/or electrically charged. Some toxic chemicals may be actively transported. The dose of a substance received by the fetus is determined by the amount of the substance transported across the placenta as well as the rate of metabolism
   Section::::Mechanisms.:Other mechanisms.
  
  Still, the placental barrier is not the sole means to evade the immune system, as foreign fetal cells also persist in the maternal circulation, on the other side of the placental barrier.
  
  The placenta does not block maternal IgG antibodies, which thereby may pass through the human placenta, providing immune protection to the fetus against infectious diseases.
   In the rare cases of survival for individuals who were in utero at the time of the bombing and yet who still were close enough to be exposed to less than or equal to 0.57 Gy, no difference in their cognitive abilities was found, suggesting a threshold dose for pregnancies below which, no life-limiting issues arise. In 50 or so children who survived the gestational process and were exposed to more than this dose, putting them within about 1000 meters from the hypocenter, microcephaly was observed; this is the only elevated birth defect issue observed in the Hibakusha, occurring in approximately 50 in-utero individuals who were situated less than 1000 meters from the bombings.
   If a woman has come into contact with a rodent during pregnancy and LCM symptoms are manifested, a blood test is available to determine previous or current infection. A history of infection does not pose a risk for future pregnancies.
  
  Section::::Cause.:Spread.:Organ donation.
  
presuppositions: The fetus has an independent immune system. If a pregnant woman eats peanut butter, her fetus could be severely allergic to peanuts.
corrections: The fetus is parasitic to the mother's system, so as long as the mother can eat peanuts there is no problem. The fetus does not have an independent immune system.
raw_presuppositions: The fetus has an independent immune system. If a pregnant woman eats peanut butter, her fetus could be severely allergic to peanuts.
raw_corrections: The fetus is parasitic to the mother's system, so as long as the mother can eat peanuts there is no problem. The fetus does not have an independent immune system.