BLOOD GROUPS BL Mtinangi Department of Physiology Hubert Kairuki Memorial University 4th December, 2015

Importance of blood grouping: Practical importance of blood grouping: Blood transfusion for treatment Paternity disputes Medicolegal use eg stain on clothes Association with suspectability to disease: eg individual with Blood group O, are more susptible to peptic ulcers while Group A to carcinoma of stomach

THE HISTORY OF BLOOD TRANSFUSION In 1901 Karl Landsteiner published his work He had discovered what we now know as the ABO blood group system He mixed samples of blood from his colleagues ABO system is still the most important Landsteiner and Weiner discovered Rh system(1940)

Karl Landsteiner (1868-1943) The discoverer of Blood Groups

HISTORY CONT. Previously it was noted that: Some people were given blood with no reaction While others received blood there was some reactions even death The best known blood groups are ABO & Rhesus systems These are of great importance in blood blood transfusion

LANDSTEINER’S LAW Landsteiner Law states that: If an antigen (agglutinogen) is present on the Rbc of individual the corresponding antibody (agglutinin) must be absent and that IF an antigen is absent on the Rbc of an individual corresponding antibody must be present in the plasma

BLOOD GROUPS Depending on the presence or absence of A & B antigens, humans can be divided into A, B, AB & O groups The antibodies reacting with the: Antigen A is called antibody A (alpha) Antigen B is called antibody B (beta) Antigen O is not antigenic and has no corresponding antibodies

THE PREVALANCE OF The prevalance of ABO blood group among the Europeans: TYPE FREQUENCY (%) O 47 A 41 B 9 AB 3

OTHER BLOOD GROUPS In addition to ABO & Rh blood groups are: M, N, P, Lutheran, Kell, Duffy, Kid, Diego etc etc These blood groups have demonstratable antigens the corresponding antibodies in the plasma are generally not present.

LANDSTEINER’S LAW Blood groups, antigens & antibodies according to Landsteiner’s law Blood group Antigens Antibodies O NO A & B A A B B B A AB A & B NO

CONFIRMATION OF LANDSTEINER’S LAW

ABO AND RHESUS BLOOD GROUPING

FORMATION OF ANTIBODIES The specific blood group antibodies (Antibodies A & B) are absent at birth, but they appear and reach a maximum concentration by the age of 10 years.

INHERITANCE OF ABO BLOOD GROUP ABO blood groups are inherited in accordance with Mendelian principle ie by a means of 3allelic genes A, B, and O. The A & B genes are codominant while O gene is functionless ie has no demonstrable product

GENETICALLY INHERITANCE OF ABO BLOOD GROUP GENETIC GENETIC GENOTY PHENOTY FROM ONE FROM OTHER PARENT PARENT A B AB AB A A AA A A O AO A B B BB B B O BO B O O OO O

ANTIGEN AND ANTIBODIES Blood Group Antigens on RBCs Antibodies in Serum Genotypes A Anti-B AA or AO B Anti-A BB or BO AB A and B Neither O Anti-A and anti-B OO

BLOOD GROUPING Before blood transfusion, the patient (recepient) and donors blood group are determined.

THE RHESUS (Rh) BLOOD SYSTEM The Rh System derives its name from the findings that the antibody produced in the rabbit by injection of Rbc from the Rhesus monkey would agglutinate 85% of human cells ie these were known as Rhesus Positive and the remaining 15% could not agglutinate & were known as Rhesus Negative

RHESUS MONKEY

RHESUS CONT. This type of antibody was also found in some people with who had transfusion before. It was also found in mothers who had given birth to a child with Haemolytic Disease of the Newborn (HDN) People who were originally labelled as Rhesus positive (Rh + ve) have actually the D antigen on their Rbc’s membrane

RHESUS CONT. Similar to D antigens are C & D antigens, but are not clinically important D antigen is much more potent ie it stimulate antibody production with greater frequency than any other Rh antigen

CLINICAL SIGNIFICANCE OF Rh FACTOR Although there are no natural antibody Rh(D) These antibodies can however develop in two ways: When an Rh Negative person is given Rh positive blood. First transfusion of Rh+ve into Rh-ve there will be no reaction. However subsequent transfusion of Rh+ve of blood causes haemolysis of transfused blood due to Anti Rh (D)

CLINICAL SIGNIFICANT OF Rh CONT. 2. When an Rh –ve mother gets a Rh +ve fetus from a Rh +ve father. First pregnancy no reaction, however subsequent pregnancies with Rh+ve fetus they will have Haemolytic Disease of the Newborn (HDN)

HAEMOLYTIC DISEASE OF THE NEWBORN

HAEMOLYTIC DISEASE OF THE NEWBORN

ERYTHROBLASTOSIS FETALIS

PREVENTION OF HDN The newly born baby blood group should be determined: If Rhesus Positive the mother should be injected with Anti D (Rhesogama) to neutrilize the babies cells that might have entered the mothers circulation. This prevent HDN in the subsequent pregnancies

TREATMENT WITH ANTI – D will prevent HDN in subsequent pregnancies THANK YOU