Rhesus factor

now we've looked at the ab0 system and I'm just going to recap that very briefly now so here we are plug group area and the blood group is determined by the red cell so this has a antigens but if someone is bug group a they're going to have B antibodies or Antibes in their plasma if someone's blood group B it's the red cells were to be but there's going to be an ta antibodies in the plasma if someone's blood group a B their blood group a B because it's the red cells that have the a and the B antigens so this is the way we've drawn an a antigen this is the way we've drawn a B antigen and as you can see there are no antibodies in the blood if someone is a B but if someone's blood group O that is blood group zero then there are no antigens on the red cells but there will be an ta antibodies and anti-b antibodies in the plasma and these antibodies are described as being naturally occurring so you're going to have these type of IgM antibodies in the plasma - any of the groupings that you don't have so blood group a is going to have the antibody B in it because there's no B antigens and it's the same with blood group B there's going to be an T a antibodies because there's no a antigen so for some reason you develop antibodies to any of the antigens you don't have and these are naturally occurring whoever you look in with the blood group a they are going to have anti-b antibodies in their plasma and these develop during the first few months to the a year of life so when a neonate is born they don't have these antibodies but they develop them in the first months and first year of life and the reason they develop them is probably because they were exposed to bacterial infections and different source of food that stimulate the development of the antibodies but we describe them as naturally occurring now the next blood group I want to introduce you to is the rhesus factor now the recess factor is so called because it was discovered using rhesus monkeys and the recess factor is actually a complicating factor with many sub groupings like C D and E sub groupings but the one that is active that is ammonia logically active that connect as an antigen is the D factor so when we're talking about the rhesus factor really what we're talking about is the D factor the letter D D factor now what the recess factor is it is an additional blood group and it's simply present or absent so if someone's blood group any as we see here we notice that there are a antigens on the surface of the red cell but we notice at the moment there are no other antigens on the surface of the red cell but if someone is a recess positive then they will have rhesus factor antigens on the surface of their cells as well and this is another antigen it's protein based and it's present or absent unlike the system it is genetically determined so what we've done now is we've added rhesus factor antigens to someone who is blood group a and we've turned them from rhesus negative into recess positive and in the same way if we look at blood group B here so we're looking at the outside of the be a wreath recite the outside of the red cell and we notice that there are B and two games but we also noticed that there are no rhesus antigens on the surface of the red cell so at the moment this diagram is illustrating someone who is B recess negative they don't have the resource but if we add the rhesus factor as an additional antigen we're making them an oblong antigen today they are actually specific molecular shapes what we've done now is we've converted this into a B rhesus positive looking at the a B we see there are a antigens on the surface and B antigens on the surface but we notice there are no rhesus factor antigens at the moment this person at the moment is recess negative they are a B negative but if we add them they will become rhesus positive so we've now diagrammatically turn these people into rhesus positive as well and finally with the blood group O we notice there are no antigens on the surface of the erythrocyte so at the moment there are no recess factor antigens so this is diagrammatically illustrating someone who is rhesus negative but if you want to diagrammatically represent someone who's rhesus positive now we see that there are the recess factor antigens on the surface of the cell this person is now a recess positive so the recess factor is mostly the D factor and it's simply present or absent so that means in addition to being a bee a bee or o someone can be either of those groups with or without the recess factor so blood groups can be a positive or a negative be positive or be negative a be positive or a be negative and a positive or a negative so that describes the blood groups simply using the rhesus system now blood groups are quite a bit more complicated than this and in fact there's a the last time I read anything about it there was 35 different types of blood groups which have been identified but the D or the rhesus are the immune illogically most significant ones to be taken into account first for blood transfusion but most transfusion laboratories will take into account more factors than the rhesus factor now we have noted that in the system there are naturally occurring antibodies in the plasma now with the rhesus factor there are no naturally occurring antibodies so if someone is recess negative there will be no rhesus factor antibodies no recess factor immunoglobulins in the plasma and whether someone's rhesus positive or rhesus negative makes no difference there still will be no recess factor antibodies in the plasma they are not naturally occurring but if someone is exposed to recess positive blood who is recess negative then that means they will be exposed to rhesus factor antigens and of course an antigen is something that causes the body to produce an antibody and immunoglobulin so if someone's recess negative and they are exposed to recess positive blood even on one occasion only because this D rhesus factor is very antigenic and Amelia logically stimulating then after that person has been exposed to recess positive blood from then on they will have recess factor antibodies in their plasma and that means if they're exposed to recess positive blood on a future occasion there can be an immunological reaction and we'll consider these in more detail when we consider the condition of hemolytic disease of the newborn

Channel: Dr. John Campbell

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Length: 9min 52sec (592 seconds)

Published: Tue Nov 17 2015