Antigens and Antibodies HELP!!!!!!!?

Question

first: what are antigens and antibodies and how are they related?

second:what role do they do in determining blood type?

third:please explain the thing where the infant or baby from the mother's placenta gets critically dangerous when their RH factor is different?????

pls. help me!!!!

Answer 1

1.Antigens are surface proteins on cells and act as a 'cell signature' for recognising cells as self or 'foreign'.

Antibodies are Y shaped proteins produced by white blood cells called lymphocytes as  part of an immune response to invasion by a 'foreign' antigen. Antibodies are specific and the two 'arms' of the antibody attach to foreign antigens rendering them harmless such as attachment to antigens on invading bactria and viruses.

2. For the ABO blood grouping system:

Individuals who are Blood group A have A antigens on their red blood cells.

Individuals who are Blood group B have B antigens on their red blood cells.

Individuals who are Blood group AB have both A and B antigens on their red blood cells.

Individuals who are Blood group O have neither A nor B antigens on their red blood cells.

Group A individuals have Anti B antibodies in their plasma so agglutinate type B or AB blood if transfused with it and can only receive type A or type O.

Group B individuals have Anti A antibodies in their plasma so agglutinate type A or AB blood if transfused with it and can only receive type B or type O.

Group AB individuals have no antibodies in their plasma so can receive blood from any blood type (Universal recipients).

Group O individuals have Anti B and Anti B antibodies in their plasma so agglutinate types A, B or AB blood if transfused with it and can only receive type O. They can donate to any other group since they do not have surface antigens which would cause an immune response in recipient. (Universal donors).

In addition, individuals are classed as Rhesus positive if their red blood cells contain a D antigen and Rhesus negative if their red blood cells lack this antigen.

3. The problem with rhesus incompatibility only occurs when a rhesus negative mother has a second (or subsequent) rhesus positive baby.

Explanation :

a) The foetal and maternal blood flow comes close together at the placenta but the blood from both does not mix.

b) This does not cause a problem for a first rhesus positive pregnancy.

c) During delivery a small portion of the baby's blood may pass to the mother and her immune system would be sensitised and produce Anti D antibodies againt the 'foreign' cells.

d) During a second or subsequent rhesus positive pregnancy the Anti D antibodies can pass across the placenta to the foetus and agglutinates (clumps together) the foetal red blood cells.

e) In severe cases this leads to haemolytic disease of the newborn and the infant would require a blood transfusion after birth.

f) Rhesus negative mothers are given an injection after delivery of a rhesus positive child to destroy any antigens she has produced so that she doesn't react during another rhesus positive pregnancy.

Sorry to be so long winded, hope this helps!

Answer 2

In the case of the pregnancy.

If a women is rh neg and the child is rh+ then at birth when the bloods can mix the mother is exposed to the rh+antigen. The first pregnancy is not a problem because moms body does not have any anti Rh+antibodies since this is her first exposure. Now after the first birth, the mothers body is producing rh+ antibodies. If she has another rh+ baby then the antibodies from mom, Igg antibodies, will cross the placenta and lyse or break the babies red blood cells and that is called hemolytic disease of the newborn. So to prevent this after the first birth the mother is given a shot of preformed rh+ antibodies, called a Rhogam shot. This will prevent her from ever forming any rh+ antibodies of her own. The shot of antibodies will be gone in about 3 months and she will not have any memory in her immune system so the next birth will be uneventful. I hope this makes sense.

Answer 3

An antibody is made in response to the antigen

There are A and B glycoproteins that are on blood cells.

People who have Blood type A have the A glycoprotein.

People who have Blood type B have the B glycoprotein.

People who have Blood type AB have both the A and the B glycoprotein.

People who have Blood type O lack A and B glycoprotein.

The A and B glycoproteins on blood, are 2 of many different examples of an antigen.

When a woman has Rh- blood and her first baby has Rh+, there is usually not a problem, but if a second baby who is Rh+, the woman starts making Antibodies to the babies Rh+ blood and this can be detrimental to both the mother and the baby.  The woman can get a shot to protect the baby and the mother from complications related to this.