1 - TITLE
2 - AIMS & OBJECTIVES
3 - ACKNOWLEDGEMENTS
4 - ABSTRACT
5 - INTRODUCTION
Basic structures and nature of ABO blood group system antigens
A and B red cell antigens
Nature of ABO blood group system antibodies
Frequency of occurrence of ABO groups
Importance of ABO blood group system
6 - MATERIALS & METHOD
ABO blood grouping method
7 - RESULTS
8 - DISCUSSION
9 - REFERENCES
AIMS AND OBJECTIVES
This work basically has an objective to find the frequency of occurrence of the ABO blood group system in Porto Novo population. It also tells which group of blood is common among the population and which group is rare in the Porto Novo people.
The research work will go a long way to serve in the future for a partial fulfilment of a degree program in health science (Haematology with transfusion science) of the Atlantic International University (AIU) Honolulu - Hawaii.
I am deeply grateful to Dr. Emmanuel Mba chief Laboratory Haematologist working in Ontario Canada who first took me into the medical technology profession.
Secondly, special thanks goes to Dr. José Brito, a general physician working at the central hospital Porto Novo who continued and persistently show interests in laboratory aspect of medicine and some of his valuable advice has been noted.
However, I sincerely thank Mr. Erineu Oliveira Rodrigues of the branch office of the Ministry of Education Porto Novo for his valuable help and computer typing of the various section of this work.
City of Porto Novo, 2009
A total of 750 blood samples were collected into the dipotassium - ethylene diaminetetra - acetic acid (EDTA) tubes and BD vacutainer tubes from the population of Porto Novo at random ranging from 2 years to 70 years of age. The ABO blood group systems were tested on the samples by the forward and reverse technique of blood grouping by tube method.
A total of 320 individuals were shown to be blood group O (43%), the blood group A were shown to be 226 individuals (30%), blood group B were 167 people (22%) and blood AB finally were 37 people making up to 5% of the population tested. This work follows almost the same discovery made by other researchers of ABO grouping system and did not show a significant differences among the groups except in that reported on Brazilian Indians in Mato Grosso which registered 100% blood group O among Indians of Mato Grosso by Bier at al(1982).
The work serves as a fundamental screening on the distribution of ABO blood group system in Porto Novo and did not indicate whether there exists a difference of ABO blood group system distribution among other islands of Cape Verde and also a reference point for those engaged in clinical blood use like the red cross organisation and paramedical units who at times give blood on emergency basis.
INTRODUCTION TO ABO BLOOD GROUP SYSTEM
The importance of the ABO blood group systems in blood transfusion lies in the frequency of their antibodies. The ABO system was the first to be recognised and remains the most important.
The vast majority of transfusion accidents that cause serious patient injury are due to an error in identifying patient samples or donor units that result in the transfusion of an ABO incompatible blood or its product. A significant number of Transfusion accidents occur however, due to ABO typing errors in the transfusion Laboratory which has resulted in many deaths.
The ABO typing test is therefore the most critical procedure encountered and performed in any given blood bank laboratory.
BASIC STRUCTURES AND NATURE OF ABO BLOOD GROUP SYSTEM ANTIGENS
The presence or absence of two antigens (A and B) defines the four blood types of the ABO blood group system. The ABO blood groups are determined genetically by the inheritance of a gene or genes that code for the production of transferase enzymes.
These enzymes are called “glycosyltransferases” which add specific hexoses (6 carbon sugars) to oligosaccharide chains present on the RBC membrane. In a series of enzymatic reactions, the ABH antigens are formed.
The first of these enzyme reactions is the addition of fucose to oligosaccharide chains on the red cell membrane by the action of Fucosyltransferase produced by the H gene. This creates the H- antigen structure that is the substrate for further transferase activity associated with the A and B genes.
The two other genetically controlled enzymes, the group A transferase (N - acetylgalactosaminyl transferase) and the group B transferase (D - galactosyltransferase) control the addition of the terminal sugars N-acetylgalactosamine and D - galactose respectively to the oligosaccharide chain that has acquired H - antigen specificity.
However, a persons ABO blood group depends on the A, B, or O gene located on chromosome 9, inherited from each parent as follows:
illustration not visible in this excerpt
A and B genes are dominant. The recessive O gene is expressed only when A and B dominant gene are absent. A person who is group O must be of the genotype OO.
A AND B RED CELL ANTIGENS
A person who inherits A gene (AA and AO) belongs to group A and expresses A antigen on their red cells.
A person who inherits B gene (BB and BO) belongs to group B and express B antigen on their red cells.
A person who inherits A and B genes belongs to group AB and express both A and B antigens on their red cells.
A person who inherits O genes belongs to group O and does not express any antigens (A or B) on their red cells.
NATURE OF ABO BLOOD GROUP SYSTEM ANTIBODIES
ABO blood group system antibodies are significantly different from those directed at other blood group system antigens because they are potent, naturally occurring antibodies found universally in immunocompetent persons.
Current thinking indicates that the A and B antigen structure on red blood cell membrane is similar to bacterial antigen structures found in the environment, these bacterial antigens stimulate production of the naturally occurring antibodies of the ABO blood group system.
However, in addition to naturally environmental stimulation, immune antibodies of the ABO system may be produced after exposure to foreign red blood cells.
Thus, individuals lacking A antigen produce Anti-A antibodies and those lacking B antigen produce Anti-B antibodies. Group O individuals lack both A and B antigen and thus produce anti-A and anti- B antibodies, were as group AB persons have both A and B antigens and produce no ABO antibodies. Group AB otherwise could be regarded as an inert serum, having no A+B antibodies.
FREQUENCY OF OCCURRENCE OF ABO GROUPS
Before talking on the frequency of blood systems of the ABO, it is a common practice in the world today to test for compatibility before blood or its product is given. However some authorities still think that group O blood is simply a universal donor and at such group O blood could be given to A, B or AB recipients freely without hindrance at all. In today’s context, there are some group O persons who are termed “DANGEROUS UNIVERSAL DONORS”.