Matthew Kim

Thank you all. Your explanations are very informative.

Hello, fellow blood bankers. I have a question about B(A) and cisAB phenotypes. These phenotypes arise from glycosyltransferases making both A and B antigens. But I don't find the difference between B(A) and cisAB phenotypes. Plus, some B(A) and cisAB alleles have the same molecular structures; for example, cisAB.05 and ABO*BA.06 have the same polymorphisms in ABO exons 6 and 7. Could you help me understand why they are classified as different phenotypes?

Thank you, Malcolm. Your advice helps me a lot. I will titrate donor plasma and use it for adsorption and elution test.

Hello, fellow blood banker. Recently, I read the AABB technical manual saying adsorption and elution should use human anti-A or anti-B. But, what does human anti-A and anti-B mean? Are they human polyclonal anti-A and anti-B reagents (in-house or commercial) or patient plasma containing anti-A and anti-B? How do your lab perform adsorption and elution test for weak A or B antigens? I look forward to hearing your answer.

Thank you, Malcolm for your kind explanation. Now I understand polyclonal is prefered over monoclonal when adsorption/elution studies are used. My another concern is how I can buy or acquire polyclonal reagents such as anti-K, anti-k, anti-kpa, anti-kpb? Particularly, all vendors sell monoclonal anti-K, not polycloanl anti-K. Since our country has no reference lab, I can not access in house polyclonal antibodies.

Malcolm Thank you for your clearcut answer. I have another question for you. Is it possible for me to perform adsorption/elution studies using monoclonal anti-K and anti-k, not polyclonal human anti-K and anti-k? AABB Technical Manual says polyclonal antibodies are preferred.

Hello, fellow blood bankers. I got a question about adsorption/elution studies for weak antigen detection. Literature describes in detail how to detect weak A and B antigens or weak D antigens using this method. However, literature describes little regarding other than these weak antigens. For example, when the Kell null phenotype is found, we need to confirm the absence of weak K and k antigens using adsorption/elution technique. Imagine that we have only anti-K monoclonal IgM and anti-k monoclonal IgG. How can I perform adsorption/elution studies for K and k antigens? My guess is that for anti-K monoclonal IgM, I can use room temperature incubation, heat elution, and immediate spin test with K+reagent RBCs, while for anti-k monoclonal IgG, I can use 37C incubation, acid elution, and IAT with k+ reagent RBCs. Do you have any opinion about this or can share your SOP with me? I look forward to your help.

Today, We performed Kell antigen phenotyping, revealing k-, Kpb-, Jsb- (genotypically predicted as positive using SNP typing). Now, I believed his phenotype is Ko. I consider further genotyping using Sanger sequencing. Thank you for your help. Matthew Kim

Thank you for Malcom. Your explanation greatly helps as always. Unfortunately, we don't have reagents such as anti-k, -Kpb, and -Jsb. We are thinking about purchasing them from commercial companies. You recommend using anti-K from different clones, but is it okay to use polyclonal anti-k from Grifols? Otherwise, we will purchase a monoclonal anti-k from a different clone. Secondly, is it okay to purchase polyclonal anti-kpa, -kpb, and-Jsb from Grifols? I am not relevant to Grifols, but I just wonder if I should go with a monoclonal reagent or a polyclonal reagent for Kell antigen typing. Once again, I appreciate your insightful explanation. Now I am staying in Liverpool for travel, so we are not far way right now.

Dear fellow blood bankers, A 50-year old patient presented with an early gastric cancer to a korean university hospital. He underwent pre-transfusion testing for pre-op work-up and the antibody identification revealed that anti-K(KEL1) was identified. The Korean population is known to have only K-k+ phenotype (100% KEL1 negative in several donor cohort studies. I thought that the patient might have been immunized to the previous transfusion from foreign donors. Suprisingly, his phenotype was K-k-. We repeated the testing, revealing the same result. We genotyped Kell groups (targeting biallelic SNPs) and his predicted phenotype was K-k+, Kpa-Kpb+, Jsa-Jsb+ compatible with that of typical Koreans. Considering anti-ku was not identified in this patient, do you think his phenotype might be a Kell null phenotype? It is my first time or my country's first time to encounter K-k- phenotype with anti-K. Could you explain this case and teach me what I can do for solving the mystery? I need your help.

Hello, fellow blood bankers. I recently got a DAT positive result; poly 4+ IgG 4+ IgA 2+ IgM1+ C3c 1+ C3d 2+ control 1+ using Bio-rad DAT card. Antibody identification revealed pan-reactivity at the IAT. I thought this result might be caused by spontaneous agglutination of heavily IgG-coated patient's red cells. According to AABB technical manual 18th ed, removing autoantibody by warm saline wash (method 2-17) is recommended for ABO, RhD cell typing. I guess warm saline washing is done to remove cold agglutinins, not IgG antibody. Is there an appropriate method to have a valid DAT result in this case? Please help me. Forgive my ignorance.

Thank you very much. Now I understand why. Your comment helps me a lot.

Wow. Now I understand the cause of C-negative phenotype. Malcolm, I am sorry for my mistake about Dw. I meant that the patient has the weak D phenotype. However, there is one thing I cannot fully understand. CdeS type has (RHD-CE(3-7)-D) on his RHD gene capable of causing altered C antigen. You previously mentioned that Trp16Cys is a source of weakened C antigen expression. Do you think that both mutated RHD and RHCE genes affect altered C antigen expression? Thank you for such a great answer.

Hello. I've tried to come up with an answer over and over, but I've failed so far. Can I ask a question here? Our patient was identified to harbor DAR/Cdes (compound heterozygote) in our commercial kit. His Rh phenotype is Dwce. (c,e antigens are strongly positive) If his Cdes (RHD-CE(3-7)-D) allele is true, the patient's phenotype should Cces. But why ce? I am looking at blood group antigen factsbook and other papers, but I cannot find an answer. Any help would be appreciated.

Thank you, Malcolm I admire you clear answer. I also appreciate your recommendation on the book, Immune Hemolytic Anemias. I will definitely read it.