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#25-OR
A NEW ASSAY TO MEASURE CELL MEDIATED RESPONSIVENESS OF RENAL ALLOGRAFT RECIPIENTS: CORRELATION TO HLA Ab.
Ronald H. Kerman, Ph.D. , Hal Gibson B.S. , Chris Garcia B.S. , Eva McKissick B.S. , Stephanie Rasmussen B.S. , Chris Ballew B.S. , Noriel Acordia B.S. , Stephen M. Katz, M.D. , Richard J. Knight, M.D. and Charles T. Van Buren, M.D. . Houston TX, University of Texas Medical School-Houston, 77030, Surgery .
Current assays measuring cell mediated responsiveness (CMR) are labor-intensive, not user-friendly and not timely requiring 3-5 days of culture incubation. A new assay (Cylex Immune Function Assay, Cylex, Inc., Columbia, MD.) for stimulation of CD4+ T cells with phytohemagglutinin (PHA) measures ATP release using a luciferin-luciferase assay. The assay is user friendly and completed within one day. The stimulation index SI, (stimulated cells/resting cells) represent the increase in CMR. We measured pre and post transplant (Tx) CMR of 96 renal allograft recipients and correlated reactivity to the presence in patient sera of Flow PRA-detected HLA antibodies (Abs), a humoral alloantigen response. The CMR for normal individuals (24±13 ng/ml ATP) was similar to pre-Tx patients (23±15 ng/ml). Patients with vs without pre-Tx HLA Abs displayed significantly higher CMRs (47±31 vs 16±11 ng/ml ATP, p <0.02). When patients were serially evaluated post-Tx (0-3, 3-6, 6-12 months) Ab positive patients, with a mean SD Flow PRA of 49±36, displayed a significantly higher CMR of 72±50 vs 7±9 ng/ml ATP, p<0.01 than recipients without post-Tx HLA Ab (0% PRA). Over the course of three years post-Tx the highly reactive CMRs (50±55 ng/ml ATP) decreased to a less reactive CMR level (12±4 ng/ml ATP) possibly suggesting a homeostatic, immunoregulatory mechanism. The results from testing this new assay to measure cell mediated responsiveness correlate with the presence of HLA Ab, as a reflection of a humoral response to alloantigen. This assay may be useful to monitor the post-Tx CMR of recipients.