Lab Med Qual Assur.  2022 Dec;44(4):204-211. 10.15263/jlmqa.2022.44.4.204.

Feasibility of Establishing a Common Cut-Off of Human Leukocyte Antigen Flow Cytometry Crossmatch Using Harmonized Protocols in a Multicenter Setting

• Bang HI
• Park Y
• Song EY
• Oh EJ
• Lee JH
• Kang ES

• KMID: 2538679
• DOI: http://doi.org/10.15263/jlmqa.2022.44.4.204

Abstract

Background
The results of human leukocyte antigen flow cytometry crossmatch (FCXM) are widely used when making transplant decisions. However, standardization/harmonization is required because the results vary between laboratories. A harmonized test method was reported to reduce interlaboratory variability. In this study, we evaluated the feasibility of establishing common cut-off values using a harmonized method in multicenter settings.
Methods
Six laboratories participated in the study and conducted FCXM using a harmonized test method. Tests were performed using two donor cells and 25 negative sera samples. As a negative control (NC), laboratory NC (Lab NC) and a common NC (Korea Organ Donation Agency [KODA] NC) were included simultaneously. Median fluorescent intensity (MFI) ratios were calculated for each NC, and means ±2 standard deviation (SD) and ±3SD were estimated for the MFI ratio.
Results
The suggested cut-off values based on the mean ±2SD and ±3SD of the MFI ratio data from 144 non-pronase T cell crossmatch after excluding one positive result were 1.6 and 1.9 using Lab NC and 1.3 and 1.5 using KODA NC, respectively. For pronase B cell crossmatch, values of 1.4 and 1.6 using Lab NC and 1.3 and 1.5 using KODA NC were obtained for the mean ±2SD and ±3SD of the MFI ratio, respectively. Inter-laboratory variations of nonpronase T cell crossmatch and pronase B cell crossmatch were less than 30% when using Lab NC and KODA NC.
Conclusions
Variations in FCXM between laboratories were within the tolerable range when the harmonized method and same negative sera were applied. Therefore, applying common cut-off values with a standardized protocol may be feasible in multicenter settings.

Keyword

Human leukocyte antigen; Flow cytometr y; Crossmatch; Harmonized method; Cut-off