Join date: 2012-01-04
Location: Woodstock Nation
|Subject: THE RHESUS SYSTEM Wed Jun 12, 2013 9:42 pm|| |
THE RHESUS SYSTEM
THE RHESUS SYSTEM
Also known as the Rhesus Factor, the Rh factor, or Rh system.
The Rhesus system was simultaneously discovered in 1937 by Levine and Stester and in 1940 by Karl Landsteiner and Alexander S. Wiener. Levine and Stetser discovered the actual D antigen, and Landsteiner and Wiener discovered the anti-D antibody.
In 1939 Philip Levine and Rufus E. Stetson published their findings about a family who had a stillborn baby who died of hemolytic disease of the newborn. The mother was aged 25 and it was her second pregnancy and she suffered blood loss at the delivery. Both parents were blood group O and the husband's blood was used to give the mother a blood transfusion, but the mother suffered a severe transfusion reaction. They investigated this transfusion reaction. Since the mother and the father were both blood group O, they concluded that there must be a previously undiscovered blood group antigen that was present on the husband's RBCs but was not present on the mother's RBCs and that the mother had formed antibodies against the new blood group antigen. This suggested for the "first time" that a mother could make blood group antibodies because of immune sensitization to her fetus's RBCs.
Karl Landsteiner and Alexander S. Wiener noticed that when 85% of human blood was mixed with rabbit blood, the antibody that was produced was similar to what happened when the test subjects were exposed to Rhesus monkey red blood cells. They also noticed that 15% of blood did not cause this problem. Through their research, the Rh Negative blood type was brought to the attention of the people responsible for blood transfusions. It's interesting to note that although the monkey proteins were subsequently found to be different than the human proteins, the name Rhesus System stuck. We now know that the Rhesus system is the second most important blood consideration other than the A-B-O type system that is discussed above. Currently, in the Rhesus system, or Rh system, there are over 100 defined blood-group antigens (proteins), among which the 5 antigens D, C, c, E, and e are the most important ones. Your red blood cells either have these proteins or they don’t. We inherit our Rh status from our parents, just as we inherit our A-B-O type.You don't have to have Rh negative parents to be an rh negative blood type. Two people who are rh positive can have an rh negative baby. This is because the rh protein is considered to be a recessive allele, just like the blood type O. Your rh positive parents can each be what is called Heterozygous, which means they carry one rh negative allele and one rh positive allele. If both parents provide a copy of the rh negative allele, then the child will be rh negative, because they have two negative alleles. If one parent donates an rh negative allele, and the other parent donates an rh positive allele, then the child will be rh positive- because the rh positive alleles are dominant. The following example illustrates the point. The left hand cell is fully rh positive, the middle cell has noticably less D (+) proteins- so that cell is considered to be weak D. A person with "weak D" blood is +/-. The cell on the right shows a blood cell with no D proteins, it is Rh negative. If your red blood cells SPECIFICALLY do not have the D protein, you are considered to be Rh D negative, also known as Rh negative, or Rhesus negative. The old way of writing this was Du or rr. The new way of writing it is dd. If you do not have ANY of the rhesus proteins, then you are considered to be rh NULL which is extremely rare. An rh NULL person is at risk any time there is blood transference, even if the donor is rh negative. Because of the specificity of blood types, it's important to note that a negative reaction can occur when ANY two "un-matched" blood types are mixed- it's not just rh negatives that are in danger of this. However, when an rh D negative produces antibodies to rh positive blood, it's a particularly potent antibody and can cause very serious problems during transfusions or pregnancy. The percentage of Rh (D) negative blood varies within ethnic groups, and is most commonly found in Caucasian peoples of European descent. The following is a breakdown of occurrence in some ethic and racial groups.
- Quote :
- Rates of Rh negative blood among ethnic and racial groups
- White - 15-16%
- African American - 8%
- African - 4%
- Basque (region of Spain/France) - 30-35%
- Asian - Less than 1%
- Asian American - 1%
- American Indian/Inuit - 1-2%
- Eurasian - 2-4%
According to Dr. Luigi Cavalli-Sforza the highest percentage of rh negative blood is in the tribes still living in the Atlas mountains, the next highest are the Basque.
In a transfusion situation, an rh (D) negative individual, should receive only A-B-O compatible rh negative blood because an rh negative body will not recognize the positive rh (D) proteins (or antigens) as SELF and will attack even an A-B-O compatible blood type if it has the additional (D) protein (antigen). Unfortunately, the availability of rh negative blood is limited by eligible, available donors and some areas of the world just don’t have much of it! In cases where no rh negative blood can be found, then the compatible rh positive blood type will be used. It’s always a good idea for rh negatives to bank their own blood, and/or have a contact list of people who could donate to you if you ever need it.
When an rh negative does not develop antibodies to rh positive blood, it’s called Sensibiliation. There has been no research done to determine why some rh negatives become sensitized and others do not.
- Quote :
- Alloimmunization or sensitization refers to the immune process that occurs when the rh negative body reacts to rh positive blood. The process of
Alloimmunization or sensitization is a simple immune response where the body detects something that is not SELF, and sends antibodies to fight it. The amount of blood exposure that causes alloimmunization varies. Some rh negative people have developed antibodies to as little 0.01 ml. of rh positive blood. There are others, (about 30% of rh negative people) who will NEVER develop an immune response, even when challenged with large amounts of rh positive blood and or repeated exposure.
50% of rh negative people who have developed antibodies will naturally purge them from their body. The antibodies do not cause personal physical harm to the rh negative individual, and only becomes a problem in a transfusion situation, or pregnancy with an rh positive child.
When alloimmunization occurs, the body produces antibodies which attach themselves to the offending antigens and essentially suffocate them. This is called Hemolysis. The process of hemolysis is called a hemolytic reaction.
In pregnancy, a hemolytic reaction in the fetus is called Hemolytic Disease of the Newborn, and can occur with any difference in the Rhesus System proteins. However, a reaction to the Rh (D) proteins is considered the most severe form of Hemolytic Disease of the Newborn and is commonly referred to as Rh Disease. Symptoms range from mild to severe and can include anaemia and heart failure.
Thanks to: http://rhnegativeblood.ning.com
Join date: 2012-01-04
Location: Woodstock Nation
|Subject: Re: THE RHESUS SYSTEM Wed Jun 12, 2013 9:43 pm|| |
FREQUENTLY ASKED QUESTIONS
What does "rh negative" mean?If you are rh negative, it means that you lack the D protein of the Rhesus system. There are actually many different blood systems that combine to give you your own specific type. The two systems that are considered to be most important are the ABO System, and the Rhesus System.
An ANTIGEN is simply anything that is recognized by your body as SELF or NOT SELF- or anything that can cause an immune response. The antigen that the medical community is referring to when they say someone is rh negative is the D antigen of the Rhesus System. You are rh D negative.
- Quote :
- In the Rhesus System, there are currently 50 recognized blood antigens, and among which the 5 antigens D, C, c, E, and e are the most important ones. (wikipedia)
Are there health risks associated with being rh negative?
YES! There are definite health risks associated with being rh negative! First and foremost is blood type incompatibility. Everyone is susceptible to blood type incompatibility, but people who are rh negative have the strongest immune response against incompatible blood. (Of course the compared response depends on how much blood is exchanged.) The antibody response associated with the D antigen is considered to be one of the most aggressive immune responses. At one time, many babies died because the consequences of mixing blood types was not known.
What happens is, the rh negative body detects blood that is not it's own, specifically it senses the D antigen. An rh negative person does not have D antigens, so it responds with antibodies to fight off the invader. It's just like what your body does when it fights a cold, except the consequences of mixing rh negative blood with rh positive blood can be deadly. The D antibodies aggressively attack the "foreign" blood cells, wrapping themselves around the cells and essentially smothering them. That process is called hemolysis. A Hemolytic reaction, or Hemolytic disease can be dangerous in any situation, but it is particularly a concern in newborns.
When an rh negative woman is pregnant with an rh positive child, there could be a serious situation if there is any blood exchange. Unless a sensitizing event has occured, it's usually not a problem in a first pregnancy for a couple of reasons. First and foremost, most blood exchange happens during delivery. Some midwives believe that the medicalization of birth has a lot to do with that statistic. Episiotomy, damage to the placenta from pushing, the forced delivery of the afterbirth, and cutting the cord too soon are just a few of the factors that can cause a blood exchange in a delivery situation.
Another reason rh incompatibility is not usually considered a problem in a first pregnancy is that it's believed to be an initially slow response. It's the subsequent exposures that cause the quicker and most severe reactions.
In a blood transfusion, the same rules apply. If it's a very small amount, and the very first time, the reaction will be slight. But, it will be a reaction, so another exposure may cause a dangerous hemolytic reaction. It's best to always be transfused with your own blood that you have donated, or a matching type.
Should I wear a medical I.D. bracelet?
It is highly recommended that you have something that identifies your ABO type and rh negative status whether that be jewelry, a card for your purse or wallet, or stored in the I.C.E. (in case of emergency) section of your cell phone or mobile device. Some people have gotten tattoos. It's important that you be identified as having rh negative blood early on in an emergency situation.
Can two rh positives have an rh negative child?
Yes! Your rhesus status is determined by both of your parents through the donation of alleles or proteins which are the building blocks for genetic expression.
Everyone has two alleles that determines rhesus status because each parent gives you an allele. An allele can be positive or negative for the D antigen in the Rhesus System. The positive (D) allele is considered dominant, and the negative (d) allele is considered recessive.
If both parents had rh positive blood, but conceived an rh negative child, then they EACH carry the rh negative recessive allele. A recessive allele will only express itself if it is paired with another recessive allele. For example, you are rh negative so you are -/-. A person who is rh negative recessive would be -/+.
To illustrate this, refer to the following tables-
For more information about inheritance and blood type, please read the following articles on this network-
Can a persons blood type change?
YES. Although it is rare.
Almost always, an individual has the same blood group for life, but very rarely an individual's blood type changes through addition or suppression of an antigen in infection, malignancy, or autoimmune disease. An example of this rare phenomenon is the case of Demi-Lee Brennan, an Australian citizen, whose blood group changed after a liver transplant. Another more common cause in blood-type change is a bone marrow transplant. Bone-marrow transplants are performed for many leukemias and lymphomas, among other diseases. If a person receives bone marrow from someone who is a different ABO type (e.g., a type A patient receives a type O bone marrow), the patient's blood type will eventually convert to the donor's type.
Also, a more common reason for a persons blood type to "change" is a mistake in the lab where the blood is being tested- and OR different protocol is used by the lab to determine blood type. For example, one lab may type a heterozygous (+/-) person as a positive, and the other lab will type the same person as a negative!
Can rh negatives get AIDS?
There has been a raging internet battle for years about whether rh negatives can get the AIDS virus or not. You're not going to find the answer to that question here, but I can say that certain blood types and factors of blood types DO AFFECT your health and immune system. So, it's not completely implausible that a certain part of the population may be immune to AIDs- we just don't know for certain who these people are yet.
The latest research seems to show that the HLA-B27 gene appears to be resistant to the AIDS virus. Most people who have this gene are rh negative... but not ALL rh negatives have the gene.
HERE is a great article that you can read about the HLA-B27 gene and the AIDS virus.
Does an rh negative have "alien" genes?
There are many websites out there exploring the concept that people who are rh negative are aliens, reptillians, hybrids etc. Some of those website will explicitly state that we are definitely reptilian. Usually the crux of their belief system surrounding this thought process is that rh negative women reject their offspring.
The problem with saying that we are aliens because of blood incompatibility is that everyone, regardless of rh status, is prone to the same situation. A person with type A+ blood cannot accept B+ blood regardless of if it came from a transfusion, or their own offspring! So, a pregnant woman with type A + or O+ blood had blood exchange with a type B+ fetus, there could very well be a hemolytic reaction! Granted, the Anti D antibodies of the Rhesus System are known for being particularly aggressive once stimulated, but blood type incompatibility is something that everyone should be concerned with, not just people with rh negative blood.
So, I guess if blood type incompatibility is the basis for the argument, then all humans are aliens.
Others say that we are aliens or hybrids because many of us seem to have "special" abilities. The most common abilities are~ empathic ability, electrical disturbance, and ESP. There needs to be more studies done on this. There is no scientific poll out there to answer this question. I have personally met rh positive people who have exhibited the above abilities, but are those rh positives heterozygous (+/-) or homozygous (+/+)? Until we actually study the phenomenon, all the talk about it is conjecture.
The fact is, no one knows for certain where rh negative blood comes from. Heck, we don't know where the different blood types come from either, nor do we know for sure how life was created on this earth. We're just guessing and hypothesizing about that stuff. There are a LOT of theories, but none have been proven beyond a shadow of a doubt. So, bottom line is- we don't know. Period.
Thanks to: http://rhnegativeblood.ning.com
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