Anti-Vel

1. Anti-Vel Providing the impossible!!

2. Test Results Sample arrived at 10.39 on Friday A Positive 11 cell Diamed enzyme panel all cells 2+to3+ 11 cell Diamed IAT panel, all cells 2+, Auto neg Enzyme cells on IAT card all cells 2+ to 3+ ? System specific antibody Tube IAT all cells 2+ to 3+ DAT - negative

3. Where to now? Scanned our additional panels for readily available high incidence antigen negative cells (k, Yta, Lub, etc) These were all positive 2+ to 3+ by IAT. Started phenotyping patient – no history of transfusion, 3 pregnancies. Hospital looking for 4 units to cover the weekend Its getting later and later and its Friday.

4. Started to phenotype patient, C +, E -, c -, e +, K-, Jk (a-b+) Fy (a-b+) M+S+s+ rare antigen typing sera, Anti-Kpb – Positive Anti-Jsb - Positive Anti-Vel – negative but with no Vel – cell to control test. What now?

5. Decided to investigate this further that evening. Selected various cells (including Vel-, Lan-, Yka-, Kna-, McCa-, McCc -, Sla -) from our Rare reference frozen cell bank (SCARF, UK cell exchange) These require to be thawed and dialysed –

6. 6/11 cells were negative All were Vel neg Remaining cells were +s to 2+ Excited!! Relieved!!! Worried!!!!! On Further examination, required a further 2 Vel negative cells to exclude all other clinically significant antibodies. Source suitable blood for patient.

7. Patient had no history of transfusion, had 3 pregnancies, born 1929. Blood was sourced from the UK frozen bank and reserved for patient. Diagnosis of MDS – requires regular transfusion.

8. IBGRL Referred further samples to Joyce Poole to confirm antibody. (with samples from 2 sons for typing) Confirmed patient as Vel neg with anti-Vel (with no additional antibodies detected) Sons tested as Vel positive but weaker than the positive control – probably due to heterozygous status.

9. On transfusion of 4th unit (April) patient had rise in temp, chills etc. Possible transfusion reaction. No evidence of serologic cause. IBGRL subsequently confirm that unit was Vel negative. 2nd unit transfused next am with no adverse reaction.

10. June, Samples referred to IBGRL for CLT assay ‘results suggest that the anti-Vel is unlikely to cause increased haemolytic destruction of transfused incompatible red cells’ BUT The CLT is based on IgG and anti VeL has both IgG/IgM components Vel pos blood is not recommended for patients with anti-Vel.

11. July, Transfusion reaction. Unit imported from USA (Auto positive IAT, unit issued as least incompatible) 2nd unit Rec’d from USA was strongly positive against patients plasma (not issued) Segments sent to IBGRL for Vel typing, confirmed as weak Vel positive. IBGRL confirmed 2nd unit as Vel- BUT patient has developed a 2nd antibody reacting to approximately 30% of Vel- cells.

12. September Red cell from Frozen bank – strongly positive (not issued). Donor previously tested as Vel-, With different anti-Vel and Patients plasma confirmed donor has weak expression of Vel antigens. Patients anti—Vel is ‘particularly avid’.

13. Patient is regularly transfused (approaching 40 units Red Cells) Now requiring HLA matched platelets on a regular basis. Frozen Bank in UK –running very low on donations <10 remaining. Other patient ongoing in UK.

14. Screening Irish population for Vel No comercially available anti-Vel (CE) Patient is the only source of anti-Vel. Samples referred to USA Rare donor program Samples referred to IBGRL Reluctant to take samples from patient for screening Adapting current automated system to screen donors No Irish Frozen Bank.