Association of HLA Types with Non-Specific Binding of Negative Control Beads in Luminex Panel Reactive Antibody (PRA) Screening Assay.
BACKGROUND
Luminex panel reactive antibody (PRA) screening assays using microbeads are widely used for organ transplantation. Anti-HLA serum reactivity is calculated by correcting for non-specific binding to the negative control (NC) beads. High mean fluorescence intensity (MFI) value of NC beads are observed in some patients and can result in false negative results in the PRA screening assay. We analyzed the clinical characteristics and HLA types of those patients with high MFI values of NC beads.


METHODS
Sixty-six patients with high MFI values of NC beads (> 300) in the PRA LABScreen Mixed assay (One Lambda) tested were included as the high NC group. Age and gender matched controls with low MFI values of NC beads (< 100) (n = 132), tested with PRA, were selected as the low NC group and 207 healthy Koreans were used as normal controls. Association of clinical characteristics and HLA types with the high NC group were analyzed using Chi-square test or Fischer's exact test, as appropriate.


RESULTS
The proportion of patients with underlying liver disease was higher in the high NC group compared to the low NC group (18.1% vs. 1.5%, p < 0.001, OR = 14.2). The seropositivity of anti-nuclear antibody and rheumatoid factor, the frequency of use of intravenous immunoglobulin G, anti-thymocyte globulin, and rituximab showed no difference between two groups. The phenotype frequency (PF) of HLA-B46 was higher in the high NC group than in the low NC group (8.0% vs. 3.2%, p = 0.036, OR = 2.8). The PF of HLA-B7 was lower in the high NC group than in the healthy controls (0.0% vs. 6.5%, p = 0.008, OR = 0.1). The PF of HLA-DR1 was lower in the high NC group than in the low NC group (0.8% vs. 6.6%, p = 0.015, OR = 0.1) or healthy controls (0.8% vs. 7.4%, p = 0.003, Pc = 0.042, OR = 0.1).


CONCLUSIONS
Increased non-specific binding to NC beads was associated with underlying liver disease and HLAB46. HLA-B7 and HLA-DR1 were related to a lower chance of non-specific binding to NC beads. The mechanism of those associations, such as differences in non-specific antibody response according to HLA phenotype or underlying disease, needs to be elucidated in further studies.
Nuri
N
Lee
Hee Sue
HS
Park
Ji Won
JW
In
Eun Youn
EY
Roh
Sue
S
Shin
Kyoung Un
KU
Park
Eun Young
EY
Song
D000328:Adult; D000906:Antibodies / Q000276:immunology / Q000378:metabolism / Q000627:therapeutic use; D000918:Antibody Specificity; D016009:Chi-Square Distribution; D005188:False Negative Reactions; D005260:Female; D006680:HLA Antigens / Q000276:immunology* / Q000378:metabolism; D015235:HLA-B Antigens / Q000276:immunology / Q000378:metabolism; D015793:HLA-B7 Antigen / Q000276:immunology / Q000378:metabolism; D015798:HLA-DR1 Antigen / Q000276:immunology / Q000378:metabolism; D006648:Histocompatibility; D006650:Histocompatibility Testing / Q000379:methods*; D006801:Humans; D007518:Isoantibodies / Q000276:immunology* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D016377:Organ Transplantation; D011237:Predictive Value of Tests; D011485:Protein Binding; D015203:Reproducibility of Results; D012189:Retrospective Studies; D055815:Young Adult
D000906:Antibodies; D006680:HLA Antigens; D015235:HLA-B Antigens; C080311:HLA-B46 antigen; D015793:HLA-B7 Antigen; D015798:HLA-DR1 Antigen; D007518:Isoantibodies