Discrepant Antibody Testing Results: Which One to Believe?

The impact of solid-phase immunoassay for HLA antibody detection on the field of transplantation has been extremely significant by providing the most sensitive and precise method for characterization of HLA antibodies. However, despite all the benefits, technical limitations and inherent artifacts represent significant challenges, particularly with Luminex-based single-antigen bead (SAB) assay. Discordant results between antibody detection (screening assay) and identification (SAB) is not uncommon. Positive SAB assay in the context of negative screening testing is well documented and attributed to altered tertiary structure of HLA molecules exposing new epitopes or detection of naturally occurring antibodies. However, there are few reports that addressed the opposite scenario when negative SAB appeared in the context of positive screening assay. In such discrepant results, unmissed HLA antibody has to be excluded with certainty by other tests; however, with the availability of variable assays it may be difficult to choose the best combinations that clarify discrepancy without adding more confusion. Here we describe the results of correlation between 2 antibody screening solid-phase immunoassays (LABScreen Mixed using Luminex and FlowPRA Screen) on conventional flow cytometry and compare their outcomes with SAB and crossmatch results.

Vascular access types in patients starting hemodialysis after failed kidney transplant: does close nephrology follow-up matter?

BACKGROUND: Native arteriovenous fistulae (AVFs) are preferred while central venous catheters (CVCs) are least suitable vascular access (VA) in patients requiring hemodialysis (HD). Unfortunately, around 80% of patients start HD with CVCs. Late referral to nephrologist is thought to be a factor responsible for this. We retrospectively analyzed the types of VA at HD initiation in renal transplant recipients followed by nephrologists with failed transplant. If early referral to nephrologist improves AVF use, these patients should have higher prevalence of AVF at HD initiation. METHODS: All patients who failed their kidney transplants from January 2002 to April 2013 were included in the study. Data regarding planning of VA by nephrologist, documented discussion about renal replacement therapy (RRT), estimated glomerular filtration rate (eGFR) at 6 months and last clinic visit before HD initiation, time of VA referral, and subsequent VA at dialysis initiation were gathered and analyzed. RESULTS: Eighty-three patients failed their transplants during study period. Data were inaccessible in six patients. Eleven patients started peritoneal dialysis (PD) while 66 started HD. Thirty-two had previous functioning VA while 34 needed VA. There were 11/34 patients (32%) with eGFR <15 mL/min at six months while 21/34 (61%) had eGFR <15 mL/min at last clinic visit before HD initiation. Only 11/34 (32%) had documented RRT discussion, 8/34 (24%) had VA referral, and 7/34 (21%) had vein mapping. A total of 30/34 (88.3%) started HD with CVC while 4/34 (11.3%) started HD with AVF (p<0.0001). CONCLUSIONS: Early referral to nephrologist by itself may not improve VA care amongst patient with end-stage renal disease.