Immunohematology and Blood Banking PDF

Common tests for immunohematology 1. Coomb’s test (Antiglobulin Test or called Anti-Human Globulin Test “AHG”) 2. RBC typing (O= 45%; A= 40%; B= 11%; AB= 4%... Rh + = 85%; USA) 3. Cross-matching 4. Antibody screening 5. Compatibility testing Antibodies attached to RBC a...

Common tests for immunohematology 1. Coomb’s test (Antiglobulin Test or called Anti-Human Globulin Test “AHG”) 2. RBC typing (O= 45%; A= 40%; B= 11%; AB= 4%... Rh + = 85%; USA) 3. Cross-matching 4. Antibody screening 5. Compatibility testing Antibodies attached to RBC as in erythroblastosis fetalis or hemolytic anemia Anti-Rh antibodies # Anti- C, anti-c # Anti-E, Anti-e # Anti-D (only) Potency (From strongest to weakest) # Anti-D, anti-c, anti-E, anti-C, and anti-e Do not bind complement (incomplete hemolysin or antibodies) IgG, active at 37 Degree Celsius. # Rh is a protein antigen Tested by indirect Coomb’s test (anti-globulin test) Lewis Blood Group (Antigen) Le gene: Codes L-fucosyltransferase, to attach fucose to subterminal unit (N-acetylglucosamine) of ABH precursor : (Lea ) Se gene: Codes a-2-L-fucosyltransferase to attach a second fucose to terminal unit (galactose) of ABH Precursor: (Leb) Lele: Co-dominant Soluble antigens, produced by tissues and found in body fluids (plasma) cont./… Lewis Antibodies IgM Can activate complement (C) leading to hemolysis at room temperature (RT). Lewis antibodies are almost always clinically insignificant because: 1. Transfused RBC shed their Lewis antigens & acquire Lewis phenotype of the recipient 2. Lewis antibodies are quickly adsorbed by free serum Lewis antigens Very rarely cause Hemolytic Transfusion Reaction (HTR) P Antigen Three types of antigens: P, P1, and Pk P antigen is a binding site for Parvovirus B19 Found in secretions as plasma & hydatid fluid cont./… P Blood Group Autoanti-P Antibodies - IgG - Can cause Paroxysmal Cold Hemoglobinuria (PCH) - Produced after some viral infections M and N Blood Group (Antigen) Rich in sialic acid TWO coding genes: Glycophorin A and B on chromosome 4 coding FIVE antigens: - M, N, S, s, and U MN system Antibodies: - IgM or IgG - Do not bind C, and active at RT Kell Blood Group (Antigen) K antigen: - Second in immunogenicity after D antigen Kell antibodies: - Anti-Kell is common - IgG (AHG test) - 20% bind complement - Can cause HDN &HTR; Linked to AID Duffy Blood Group (Antigen) Three alleles: Fya, Fyb, and Fy (silent) Four antigens: Fy3, Fy4, Fy5, and Fy6 (all normal RBC are positive for them) Duffy Antibodies: - IgG; reacts best via AHG - Do not bind complement - Cause acute and delayed HTR; & HDN Kidd Blood Group (Antigen) Three alleles: Jka (JK1), JKb (JK2), & JK3 Kidd antigens transport urea in RBC Kidd antibodies: - IgG - Can cause HDN, and delayed HTD - Anti-JK3: Jka- JKb- (rarest type) Autoimmune Hemolytic Anemia (AIHA) RBC destruction by autoantibodies (Aab): # IgG or IgM, or more rarely IgE or IgA If fix C, it causes intravascular hemolysis, but if not, it causes extravascular hemolysis Ab coated RBC: Lose membrane by Mc in the spleen, then forming spherocytosis. AIHA, according to thermal specificity of Aab: 1. Warm Ab: Bind at 37o C, 80% of cases, and majority are IgG against Rh antigens 2. Cold Ab: Bind at 4o C, 20% of cases and are IgM and fix complement (see next slide). Warm autoimmune hemolysis Common in middle age and females 50% no underlying cause, but others are due to lymphoid neoplasms, solid tumors, C.T. disease as SLE, drugs as penicillin & others. Cold autoimmune hemolysis 1. Chronic : Affects elderly; with B cell lymphoma; antibody is monoclonal against Ii antigens 2. Acute: With Mycoplasma pneumoniae, IMN, & PCH*; Ab is polyclonal against P antigen * In children with congenital syphilis