Other Blood Group Systems (Part II) - PDF

Faculty of Applied Health Science Technology Medical Laboratory Technology Department Blood Banking HLBB-401 Other Blood Group systems (part-II) By Dr. Hadeel Said MD clinical hematopathology  ILOS Define antigen,antibodies...

Faculty of Applied Health Science Technology Medical Laboratory Technology Department Blood Banking HLBB-401 Other Blood Group systems (part-II) By Dr. Hadeel Said MD clinical hematopathology  ILOS Define antigen,antibodies, sensitization and agglutination Define cold and warm reacting antibodies List the other blood group systems Describe lewis system Describe Ii, P, MNSs systems List the warm blood group systems  Introduction Antigen Antigen is a substance, which elicits immune response. Antibody The antibodies are immunoglobulin in nature.  Introduction Clinical significance: antibodies that are associated with red cell destruction Haemolytic Transfusion Reaction (HTR) Haemolytic Disease of Newborn (HDN) Not clinically significant: antibodies that do not cause red cell destruction  Introduction Sensitisation The sensitisation is defined as binding of antigen and antibody, in vitro or in vivo, with or without agglutination. Agglutination Whenever the sensitized cells come into contact of each other, the result is clumping of red cells known as agglutination.  Introduction Grades of agglutination The agglutination results are graded from 1+ to 4+. The American Association of Blood Banks (AABB) recommends the following grading system: 4+ = One solid aggregate of red cells 3+ = Several large aggregates 2+ = Medium sized aggregates with a clear background 1+ = Small aggregates with a turbid background giving granular appearance. Weak (w) = Tiny aggregates are seen only under microscope Negative = All cells are free.  Introduction Cold reacting antibodies: agglutination best observed at or below room temp. Warm reacting antibodies: agglutination best observed at 37°C  Immunoglobulin immunoglobulin (Ig), antibody (Ab) ,is a large, Y-shaped protein produced mainly by plasma cells that is used by the immune system to neutralize pathogens such as pathogenic bacteria and viruses  Immunoglobulin classes The immunoglobulins can be divided into five different classes: 1. IgG - Gamma heavy chains 2. IgM - Mu heavy chains 3. IgA - Alpha heavy chains 4. IgD - Delta heavy chains 5. IgE - Epsilon heavy chains Immunoglobulin Subclasses  Immunoglobulin - G Major Ig in serum Major Ig in extravascular spaces Only Ig that crosses placenta  Immunoglobulin - M Third most common serum Ig. First Ig to be made by the fetus First Ig to be made by B cells when stimulated by antigen  Blood group systems There are thirty five current human blood group systems. ABO blood group system Rh blood group system The ABO blood group system is the most important blood group system in human blood transfusion then the Rh system.  Other Blood Group Systems Beside ABO and Rh there are other blood group systems, but of less clinical signifiance. Their testing is not carried out as a routine. The antibodies of this system have also been found causing haemolytic transfusion reaction (HTR) and haemolytic disease of newborn (HDN).  Other Blood Group Systems Lewis I P MNSs Kell Kidd Duffy  Lewis antigens The two antigens are: Lea and Leb.  Lewis antibodies Lewis antibodies are cold reacting IgM antibodies which bind complement. There are mainly two antibodies acting against two antigens.  Lewis Antibodies No clinical significance…Why? - Le antibodies in a patient can be neutralized by the Lewis antigens in the donor’s plasma (cancel each other out) - Transfused red cells shed their Lewis antigens and acquire the Lewis phenotype of the recipient  Lewis Antibodies Do not cause HDN : Because they do not cross placenta  Ii blood group system The Ii system was discovered by Wiener, et al in 1956. Antigens The I antigen is present on the red cells of almost all individuals. Very rarely in the absence of I antigen, another antigen i may be present.  Ii blood group system Antibodies Anti-i It is a cold reactive IgM antibody, which readily binds complement. It rarely causes HTR. Anti-I Anti-I is a cold reactive autoagglutinin.. The antibody is clinically insignifiant.  P blood group system Discovered by Landstiener in 1927. Antigens The main antigens of the system are: P1 and P  P blood group system Antibodies Anti-P1 It is a cold reactive IgM antibody. This is a clinically insignifiant antibody. Anti-P This antibody too reacts best at room temperature, in spite of being IgG in nature. The anti-P is associated with recurrent abortions. It may cause HTR.  MNSs blood group system MN was the second blood group system discovered after ABO, by Landstiener Walsh and Montgomery in 1947 described Ss system, which was found to be close to MN.  MNSs blood group system Mns antigens The MNS antigens are well developed at the time of birth and can be detected on foetal cells. The four types of antigens of the system are M, N, S and s.  Anti-M and anti-N antibodies IgM Clinically insignificant reacts at room temperature  Anti-S and Anti-s Clinically significant IgG Can cause RBC destruction (HTR) and HDN These are warm reactive antibodies  Kell blood group system Are common in whites but rare in Indians and Arabs. Antigens Usually the antigens are K and k The K antigen is very immunogenic (2 nd to the Rh antigen) in stimulating antibody production  Kell antibodies IgG Produced as a result of immune stimulation (transfusion, pregnancy) Clinically significant  Kidd blood group system The blood group picks its name from a patient, Mrs Kidd, in whose serum the antibody was first discovered. Antigens The two types of antigens of the Kidd system are : JKa and JKb. Antibodies Anti-JKa and anti-JKb are IgG antibodies The antibodies cause mild HDN and delayed HTR.  Duffy blood group system Like Kidd this blood group system too owns its name to a patient, a haemophiliac, Mr Duffy in 1950. Antigens The antigens of the system are called: Fya and Fyb.  Duffy blood group system Antibodies Anti-Fya and anti-Fyb are warm reacting antibodies. They are capable of causing HTR and HDN.  Duffy blood group and malaria An association between Duffy blood group system and malaria has been observed. The Duffy individuals are found to be resistant to a West African malarial parasite THANK YOU