#60
MONITORING FOR ANTI-HLA ANTIBODY MAY BE IMPORTANT POST ATG.
Isabelle G. Wood, BS , Fang Ji MA and Edgar L. Milford, MD . Boston MA, Brigham and Women
s Hospital, 02115, Tissue Typing Lab and New England Organ Bank .
A 42 year old multiparous female received a 1 haplotype matched kidney from her 68 year old mother. She was 0% PRA by CDC T and FlowPRA Class I and II pre transplant. Flow and CDC T and B cell crossmatches were negative pre transplant. At implantation, the kidney, which was laporascopically removed, appeared ischemic. Though she made 700cc of urine on day 1, she had poor renal function on Thymoglobulin (ATG) induction therapy. A day 5 biopsy showed ATN and C4d negative fluorescence. ATG was discontinued on day 15; a day 31 transplant nephrectomy showed coagulative necrosis. The purpose of this study was to monitor the ATG and anti-HLA antibodies correlated with clinical outcome. Post transplant flow crossmatches and FlowPRA were negative until day 63 when there was a slight rise in FlowPRA Class I and II. By day 81, the PRA Class I was 16% and II was 51% with specific anti-HLA antibodies against donor antigens causing positive crossmatches. As soon as ATG levels declined, anti-HLA antibodies became detectable (see figs). 
2/5 patients tested (including patient above) showed a rise in PRA as ATG levels subsided. ATG bound to both T and B cells when stained with patient serum during therapy at day 1-30 (left figure). The role that ATG may play in blocking the development and detection of antibodies or affecting recipients memory B cells is unclear. More patients need to be screened in the early weeks post ATG.