Physiology 8 9/29/13 12:15 PMToday we’ll talk about the blood groups: classic and minor

Classic (Major) ABO groups: these are antigens that are present on the surface of

RBCs A and B antigens: either they are together or separate as AB

antigen. Or sometimes, in some individuals these two antigens are not present on the RBC and is therefore the O group

the fifth blood group: rhesus, RH or D blood group antigen or agglutinogen Type A

o Antigen A on the surface/ membrane of the RBC o in these individuals, in their plasma, there re antibodies or

agglutinines Anti-B or beta Type B blood group:

o Antigen B and in the plasma alpha antibody AB blood group

o Both antigens are present on the RBC’s: antigen A and B o no antibodies in the plasma

Type O:o No antigens, no A nor B antigens on the membrane of the

RBC’s o but there are two antibodies: alpha and beta or agglutinin

anti- A and B these antigens are also present in other tissues: salivary glands,

pancreas, kidneys, liver, lungs, testes, semen and _____ fluid these antibodies which are present in plasma are usually not traced

in the newborn baby: therefore, newborn baby plasma does not contain these antibodies

till about the second month after birth, only then they may occur naturally

sometimes, but only rarely, they don't occur at all during the life of that individual unless that individual is exposed to the RBC’s of the opposite individual (I think he means an individual with different blood type)

the occurrence of these antibodies is may be because of the injection of antigens present in the food of animal sources or exposure to some kind of bacteria.

the concentration of antibodies increases gradually after the 7th month of life and then they decrease, reaching a low level, at the age of 80-100

on the surface of the RBC’s, there are hundreds of antigens besides the classical blood group

o more than 100 blood antigens have been described, out of which at least 15 have been identified

o blood group systems exist in most racial groups, of these only two or of major importance clinically: ABO and rhesus blood group

o these are the most important antigens of the minor blood groups: MM,MN, NN, PP, Pp, KELL, LEWIS, KID, LUTHERAN, Duff, etc.

o sometimes, especially the first three, they produce problems in the human being: these antigens may produce antibodies which results in agglutination between the RBC’s and the newly produced antibodies

when we say blood Group A, this refers to a phenotype of an individual: how about the genotype of that individual

o A is either AA or AO o B is either BB or BO o AB, simply AB (dominant, both)o and O: OO (recessive)

The rhesus blood group system o In Europeans, 85% of individuals’ RBC’s have the D antigens

but no antibodies in their plasma: these are called Rh/ D-positive

o the remaining 15%: neither antigen or antibody is present, these are called Rh/ D-negative

o there are at least three sets of alternative antigens in the Rh group system: D or d, C or C and E or e.

o D is the strong antigen and therefore clinically more important than others

o in blood banks, Rh grouping is performed with anti-D serum The Distribution of Blood Groups in the US:: please refer to the

slideso Whites: A41, B10, AB4, O45, Rh-positive 85, Rh-negative 15o Blacks: it's different... o Chinese: higher AB than both whites and blackso Indians: notice, no B, no AB, and only 3 A.... 97% of them are

Oo Jordanians: in a study based on 400 students

Ganong’s Review o This is from last year, again refer to the slide

Guytono Another resource, same pattern only small numerical

differences The importance of the rhesus blood group comes into play in the

following scenario: if a man of Rh-positive marries a woman with Rh-negative blood type, their baby will be Rh-positive

o Antibodies will pass from mother to fetus, agglutination occurs and hemolysis may occur in the fetal blood and will cause death

Probabilityo DD male x female dd

DD x dd Dd, Dd, Dd, Dd in this case, all the babies are positive

o Dd male x female dd Dd x dd Dd, Dd, dd, dd 50% chance therefore an Rh-positive father with an Rh-negative

mother may not always produce Rh-positive babies Hemolytic Diseases due to incompatibility

o There are 3 conditions in which the mother will develop antibodies

o the first is: blood transfusion premarital from an Rh+ person

o the second: leakage during pregnancy of small amount of fetal blood into maternal blood, this is referred to as placental hemorrhage

this is dangerous especially during the 3rd month because there is time for the mother to develop antibodies and for them to pass into the fetal blood where agglutination will occur

o During delivery, some blood is secreted back to maternal blood: in this case, the second baby will be in danger whereas the first two, the delivery baby of the current pregnancy is in danger

o In these conditions, one of the following hemolytic diseases may occur

If antibodies pass into fetal blood, hemolysis occurs and is classified according to severity

mild: the newborn is said to have mild hemolysis or erthryroblastosis fetalis: small amount of RBC’s leak into mother circulation, some mothers develop antibodies against D antigens. These antibodies pass to feral blood and cause mild hemolysis of RBC’s of the fetus

this newborn baby can be rescued by giving him Rh- blood but not from his mother because she has the antigens. And no Rh+ otherwise agglutination will occur

moderate: leterus graves nenatorum. The infant is born at term, with jaundice, or becomes so within 24 hours. Mental retardation may occur.

Hydrops fetalis: severe. This depends on the amount of antibodies that pass into the fetal blood. Infant may die in uterus or may develop severe anemia, jaundice and edema and dies within a few hours

o this is no problem. It can be prevented by giving an Rh- mother human gamma globulin against Rh+ RBC’s within 72 hours after she has delivery an Rh+ infant. These antibodies bind to an antigenic sites on any Rh+ RBC that may have entered the mother’s blood during delivery and prevents them from inducing antibody synthesis by the mother. Usually given within 48 hours.

in donating blood, this diagram has to be taken into considerationo O is a general donor who donates to everyone including its

own kind, receives only form its own kinds o AB on the other hand is called the general/ universal recipient

who receives from anyone and its own kind o A and B from their own kind and O o one unit of blood: around 450 mL. o Why does agglutination not occur within an A group with an O

donor? It occurs, but at a minor scale and is diluted. o therefore, O is not always a general donor nor AB is a general

recipient: only up to 2 bags or 900 mL then we have to resort to the same kind

o you may be wondering whether ABO incompatibilities are also a cause of hemolytic disease of the newborn

for example, a woman with Type O blood has natural antibodies to bother A and B antigens. If her fetus is type A or B, these, in theory, should cause a problem. Fortunately, it doesn’t because A and B antigens are not strongly expressed in fetal RBC’s and partly because natural antibodies are of the IgM type which do not cross the placenta

the fetal blood doesn’t easily recognize the antigens A and B. the IgM antibodies don’t pass into the fetal blood

9/29/13 12:15 PM

9/29/13 12:15 PM