Dear Marcia, Here is a quick summary of the immunobiology of antibodies, autoimmune disease, pregnancy & lactation. Our bodies make several types of antibodies. For this discussion the two main types are IgG and IgA. IgG is transferred during pregnancy from the mother's circulation into the babies circulation. There is an accumulation of antibodies over the course of the pregnancy. Thus, a baby born prematurely would not yet have received all the antibodies that a term baby would receive. These IgG antibodies will remain in an infant's circulation for around six months and then they disappear. In the meantime, the infant has not yet developed the full capacity to make it's own antibodies yet. This is just one reason why it is so important for the infant to receive antibodies from breastmilk (and I will explain why these antibodies are special further on). IgG antibodies are great for getting rid of bacteria and viruses in the blood or tissues. When IgG binds to a bacteria this activates a collection of proteins known as complement. These proteins coat the surface of the bacteria or virus and poke holes in it so that it will die. Very effective system, although it also induces inflammation. However, if a person has an autoimmune disease they will make antibodies against their own proteins. In this case, the mother's body makes IgG antibodies against her own neutrophils. The anti- neutrophil IgG binds to the surface of her neutrophils, complement gets activated, and pokes holes in the cells causing them to die. This explains why she has fewer neutrophils. Neutrophils are the "first responders" of all our immune cells and they are especially good at killing bacteria. Someone who is neutropenic may have trouble clearing bacterial infections. Now as I mentioned, the IgG from the mother is transferred to the fetus during pregnancy. This would include the anti-neutrophil IgG antibodies that the mother is producing. So, her baby is receiving these antibodies in utero. This is not a problem because the baby is also protected from infection in the womb. However, after the baby is born it will still have these antibodies in it's system for about six months which could cause the baby to be neutropenic for awhile as well. This also happens with neonatal lupus: the maternal autoimmune antibodies are passed to the baby during gestation and the newborn will have lupus symptoms for about six months until those antibodies wear out. Now here's the great news. The main antibody in breastmilk is IgA and it works in a different way than the IgG type. This IgA type of antibody is produced on all our mucosal surfaces (the lining of the respiratory tract & the lining of the gastrointestinal tract) which are the main places where we encounter bacteria and viruses. The first thing that the bacteria or virus needs to do to infect us is to bind to the lining of our respiratory or GI tract, BUT the IgA type of antibody binds to the bacteria or virus and actually BLOCKS it from binding to us at all. In other words, it can prevent infection from even being established. Or reduce it to the level where there aren't any symptoms. This mechanism also does not cause any inflammation. So, after this baby is born it may be slightly neutropenic and therefore more susceptible to infection. However, if the mother is breastfeeding, the IgA antibodies in the milk will work to prevent infections from being established in the first place. Therefore, the baby may have fewer neutrophils for awhile, but that shouldn't matter because it will be well protected by the IgA antibodies that it will receive through the breastmilk. Also, the IgA antibodies are designed to travel through the digestive tract without being degraded. I hope that this information is helpful. Feel free to contact me offlist if you have additional questions. Warm regards, Laurie Shornick, PhD *********************************************** Archives: http://community.lsoft.com/archives/LACTNET.html To reach list owners: [log in to unmask] Mail all list management commands to: [log in to unmask] COMMANDS: 1. To temporarily stop your subscription write in the body of an email: set lactnet nomail 2. To start it again: set lactnet mail 3. To unsubscribe: unsubscribe lactnet 4. To get a comprehensive list of rules and directions: get lactnet welcome