P104 HLA autoantibody following a pancreas transplant: A case study

Abstract

A 38 year old Caucasian male who had received a haplo-identical living donor kidney transplant 6 years prior was transplanted with a deceased donor pancreas. The patient had no HLA antibodies at the time of pancreas transplant. The pancreas donor was a 5 antigen mismatch (DR homozygous) with the recipient, and a 1 B-locus match with the prior kidney donor. A routine, not for cause, donor-specific antibody (DSA) test collected 42 days post pancreas transplant showed high levels of antibody, including strong antibodies to the recipient’s own B60 (B∗40:01, MFI = 5900) and DQ8 (DQA1∗03:01/DQB1∗03:02, MFI = 2500). The DSA test was repeated and the clot was DNA typed to confirm it was from the recipient. The pancreas donor was a 24 year old Caucasian female who had recently given birth. Testing of a donor serum sample showed the same class I antibody profile as the recipient, including B∗40:01 (MFI = 7800). However, the class II profile was different. Instead of the DQ7, DQ8, DQ9 antibodies seen in the recipient, the donor primarily had antibody to DR4, DR7, DR9 and DQ4; the DQA1∗03:01/DQB1∗03:02 bead was negative. PCR-SSP typing of B cells isolated from the recipient’s peripheral blood on day 69 showed no evidence of the pancreas donor’s HLA type. Another routine DSA sample obtained on day 181 post-transplant showed only anti-DQA1∗05 against the kidney donor and had none of the donor’s antibodies. We believe the transient antibody against the recipient’s own HLA was likely due to pregnancy-induced donor B cells in the lymph nodes transplanted along with the pancreas. The difference in class II antibodies may have been due to reactivation of memory B cells upon exposure to recipient DQ8 antigen. The recipient suffered no ill effects from these antibodies and continues to do well.