Posted January 10, 20232 yr comment_84749 Good morning friends! I hope everyone is doing well and having a nice start to 2023! I am hoping to get some input from the group on current practices for mismatch kidney transplants. Specifically, B patients receiving A subgroup Kidneys. Currently, we send out for a DTT treated Anti-A titer but the lab will no longer be able to provide this service for us. I made some calls to the area hospitals and reference labs to find out what the majority do and - I found it is a mixed bag. What do you do when it comes to pre and post titers for these types of transplant patients? Thank you for all your insight, as always! Sara
January 10, 20232 yr Solution comment_84751 Somewhere, in Patrick Mollison's work, cited in Blood Transfusion in Clinical Medicine, he mentions that IgG ABO antibodies are more clinically significant in solid organ transplants than are IgM (if I remember correctly, he specifically mentioned renal transplants), but I cannot cite the exact paper off the top of my head (I will see if I can find the reference). As a result, whenever we were dealing with a renal transplant that crosses the ABO barrier, we almost performed an IgM and an a separate IgG titre. Whether this is now considered to be necessary, I will leave to other people to discuss!
January 11, 20232 yr comment_84760 Our Blood Bank performs A1 lectin testing of the potential A donor. If they are positive, they are eliminated as a donor. as for the recipient - all B patients (potential mis-match recipients) are titered against an A subgroup cell (A2 reagent red cells here) to determine their antibody reactivity. The clinicians have an established threshold for a suitable titer (which I do not know) Potential B recipients who have an Anti-A titer with A subgroup cells below the established threshold could potentially receive an A subgroup kidney. As for O recipients - we make our own 0.01MDTT treat their plasma to determine IgG vs IgM antibody reactivity titers.
January 12, 20232 yr comment_84765 21 hours ago, Bet'naSBB said: Our Blood Bank performs A1 lectin testing of the potential A donor. If they are positive, they are eliminated as a donor. Wow. That eliminates ~80% of group A potential donors.
January 12, 20232 yr comment_84769 1 hour ago, exlimey said: Wow. That eliminates ~80% of group A potential donors. That's still a significant number of A subgroup kidneys to give B patients. Patients who are type B and need a kidney transplant usually have to wait years, and sometimes die because no type B kidney is available.
January 12, 20232 yr comment_84772 1 hour ago, Baby Banker said: That's still a significant number of A subgroup kidneys to give B patients. Patients who are type B and need a kidney transplant usually have to wait years, and sometimes die because no type B kidney is available. Agreed. No criticism was intended, I was just surprised at that approach. So by reading between the lines, the logic is that by transplanting a kidney from a donor with a weaker expression of A antigen (A2), the group B recipient/host is less likely to detect/reject it ? Did I get that correct ? Just curious, can one give a group A1 kidney to a group B patient who has a very low isoagglutinin titer ?
January 12, 20232 yr comment_84777 "Just curious, can one give a group A1 kidney to a group B patient who has a very low isoagglutinin titer ?" It's been done. Depends on the ability to suppress the anti-A titer low enough through immunosuppressive drugs and plasma exchange, the usual preparative regimen. Obviously ABO identical is best, but this is an alternative at some centers with experience doing these transplants.
January 12, 20232 yr comment_84778 28 minutes ago, Neil Blumberg said: It's been done. Depends on the ability to suppress the anti-A titer low enough through immunosuppressive drugs and plasma exchange, the usual preparative regimen. Obviously ABO identical is best, but this is an alternative at some centers with experience doing these transplants. Thanks. Probably an unanswerable question: How low a titer is "low enough" ? A follow-up.....can one transplant an A1 kidney into an A2 patient with anti-A1 ?
January 12, 20232 yr comment_84779 3 hours ago, exlimey said: Thanks. Probably an unanswerable question: How low a titer is "low enough" ? A follow-up.....can one transplant an A1 kidney into an A2 patient with anti-A1 ? I don't know what the titer is for incompatible kidney transplant, but for hearts they prefer less than 1:4, but there are other criteria as well. If the patient is less than 12 months old, they don't worry as much about the titer. I think they won't consider a patient who is over 2 years old. Again though, that is for hearts.
January 13, 20232 yr comment_84782 15 hours ago, Baby Banker said: I don't know what the titer is for incompatible kidney transplant, but for hearts they prefer less than 1:4, but there are other criteria as well. If the patient is less than 12 months old, they don't worry as much about the titer. I think they won't consider a patient who is over 2 years old. Again though, that is for hearts. This is fascinating stuff. A lot of science, learned the very hard way, with a heavy dose of art. I don't envy those having to make these calls.
January 13, 20232 yr comment_84784 On 1/10/2023 at 4:04 PM, Malcolm Needs said: Somewhere, in Patrick Mollison's work, cited in Blood Transfusion in Clinical Medicine, he mentions that IgG ABO antibodies are more clinically significant in solid organ transplants than are IgM (if I remember correctly, he specifically mentioned renal transplants), but I cannot cite the exact paper off the top of my head (I will see if I can find the reference). I cannot find the reference for which I was looking, and I wonder if (now I am in my dotage) I have mis-remembered and that it was one of a couple of papers stating that IgM ABO antibodies are easier to inhibit than are IgG ABO antibodies. The references for these are Witebsky E. Interrelationship between the Rh system and the ABO system. Blood 1948; 3: 66-79, and Kochwa S, Rosenfield RE, Tallal I, Wasserman LR. Isoagglutinins associated with erythroblastosis. J Clin Invest 1961; 40: 874-883. My apologies.
March 13, 20232 yr comment_85223 UNOS has guidelines on off-type kidney transplants. We were using the UNOS protocol for DTT treated iso-titers, but have transitioned to running IgG and IgM iso-titers on our NEO Iris. https://community.asn-online.org/blogs/mark-lerman/2018/07/09/weekly-rewind-abo-incompatible-kidney-transplant-r https://optn.transplant.hrsa.gov/media/2347/mac_guidance_201712.pdf
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