Transplanting tissue and blood

Question 1

why do transplanted organs or tissues produce an immune response?

Answer 1

-due to the presence of non self antigens if they come form someone else

Question 2

what are the two exceptions if transplants that do not produce an immune response? and why?

Answer 2

-transplants within the same person e/g/ skin grafts
-transplants that occur between identical twins as they are genetically identical and so have identical antigens

Question 3

what is the process of transplant rejection?

Answer 3

-t lymphocytes are stimulated by the non self antigens on the transplanted tissue
-t cells are cloned by mitosis to form killer t cells and other cells
-the killer t cells destroy the transplanted tissue

Question 4

what are the procedures that can help prevent transplant rejection?

Answer 4

-tissue typing
-immunosuppression techniques
-x-rays

Question 5

what is tissue typing? where does the best tissue typing occur between?

Answer 5

-matching the donor and recipient antigens so that there is as good a match as possible e.g. little difference
-close relatives and identical twins

Question 6

what are immunosuppression techniques?

Answer 6

-use of drugs to inhibit DNA replication which stops the cloning of lymphocytes and so stops the production of killer t cells
-for many transplants these drugs have to be taken for a very long time sometimes for life

Question 7

what are x rays and how do they prevent transplant rejection? how is it used?

Answer 7

-used to stop the production of lymphocytes through radiation of bone marrow or lymph tissue
-this causes unpleasant side effects and so is used as a back up to immunosuppression drugs

Question 8

what are the disadvantages of using immunosuppression drugs/ x rays?

Answer 8

-they compromise the individuals immune system
-makes them susceptible to infection as it depresses/ weakens the immune system in general

Question 9

what are the three ways individuals who undergo immunosuppression techniques are protected against infection?

Answer 9

-anti viral drugs
-anti bacterial mouth washes
-use of monoclonal antibodies to reduce the effect of t cells involved in rejection

Question 10

do red blood cells have antigen?

Answer 10

-yes

Question 11

why are antigens for a certain blood type e.g. type A switched off during early development if the individual has type A blood?

Answer 11

-so that an immune reaction is not triggered

Question 12

what are the 4 blood groups? and what is this categorisation an example of?

Answer 12

-A B AB O
-polymorphism

Question 13

why can blood be donated from a donor who as type A to a recipient who also has type A?

Answer 13

-the recipient has no a-antibodies that correspond to the A antigens on the donor’s blood cells

Question 14

why can blood not be donated from a donor who has type A to a recipient who has type B?

Answer 14

-the recipient has anti a- antibodies in their plasma
-the presence of the A antigens from the donors blood and the anti A- antibodies causes an antigen- antibody reaction
-this causes blood to agglutinate which blocks capillaries and can lead to organ failure or even death

Question 15

what type of antigens and antibodies does blood group A have?

Answer 15

-A antigens
-anti B- antibodies

Question 16

what type of antigens and antibodies does blood group B have?

Answer 16

-B antigens
-anti B- antibodies

Question 17

what type of antigens and antibodies does blood group AB have?

Answer 17

-both A and B antigens
-neither A or B antibodies

Question 18

what type of antigens and antibodies does blood group O have?

Answer 18

-neither A or B antigens
-both anti A and anti B antibodies

Question 19

what blood groups can and cannot receive blood donation from group A and why?

Answer 19

-group A can (has A antigens)
-group B can’t and so will agglutinate because it has anti A- antibodies
-group AB can as it doesn’t have anti A or B antibodies
group O can’t as it has both anti A and B antibodies

Question 20

what blood groups can and cannot receive blood donation from group B and why?

Answer 20

-group A can’t so will agglutinate as it has anti B antibodies
-group B can as it has B antigens
-AB can as it doesn’t have A or B antibodies
-O can’t as it has A and B antibodies

Question 21

what blood groups can and cannot receive blood donation from group AB and why?

Answer 21

-both group A and B cant and will agglutinate as they contain the A and B antibodies
-AB can
-O can’t as it contains both A and B antibodies so will agglutinate

Question 22

what blood groups can and cannot receive blood donation from group O and why?

Answer 22

-all blood groups can receive O as it doesnt contain A or B antigens

Question 23

what blood group is the universal donor?

Answer 23

-O

Question 24

what group is the universal recipient?

Answer 24

-AB

Question 25

why do we have an ABO system? is there a best blood group?

Answer 25

-its thought that blood groups have mutated through time which explains why we still have these 4 blood groups
-the mutations are described as neutral as they offer not advantages to any of the blood groups

Question 26

what is another blood system that doctors use?

Answer 26

-the Rhesus system

Question 27

what is the rhesus system based on?

Answer 27

-the presence or absense of antigen D on red blood cells

Question 28

how much of the population are rhesus positive (Rh+)?

Answer 28

-around 85%

Question 29

what is the difference between the antibodies in the ABO system and the anti-D antibodies in the Rhesus system?

Answer 29

-the anti-D antibodies do not occur naturally in the blood plasma

Question 30

why will someone who is Rhesus positive not produce anti-D antibodies?

Answer 30

-the relevant B lymphocytes will be switched off when the Rhesus positive marker is recognised as self during development

Question 31

why do some Rhesus negative individuals produce anti-D antibodies?

Answer 31

-if their blood is contaminated with blood containing antigen D

Question 32

how many a Rhesus negative’s blood become contaminated with antigen D?

Answer 32

-through a blood transfusion between an Rhesus positive and negative recipient
-when a Rhesus negative mother has a Rhesus positive baby

Question 33

what is the sequence of events that lead to a Rhesus negative mother’s blood being contaminated by their babies Rhesus positive blood?

Answer 33

-during birth some of the babies RBC’s which contain antigen D leak into the mothers circulation
-causing the mother to produce anti D antibodies (by this time the baby and mother are separated so it wont cause harm to the baby)
-during future pregnancies if the baby is Rhesus positive the necessary B lymphocytes are already sensitised so will produce large amounts of anti-D antibodies quickly
-these can cross the placenta and cause agglutination of foetal RBC known as haemolytic disease of the newborn

Question 34

is haemolutic disease of the newborn common today and why?

Answer 34

-no
-Rhesus negative mothers are given an injection of anti D antibodies during pregnancy
-which attach to babys RBC that contain antigen D that have moved to the mothers circulation before her b lymphocytes are sentised
-72hrs after birth if the baby is Rhesus positive the mother is given another injection of anti-D antibodies