Main problem

Luminex panel and single antigen beads (SAB) are used for screening and DSA specificity determination respectively. The cost of SAB may limit its general use, so some labs perform SAB tests only after positive screening.

Methods

We compared both strategies: 1) SAB only if positive screening with kits from manufacturer A, and 2) direct SAB from manufacturer B, and correlate their sensitivity with histological findings.

Results

We selected 118 kidney transplant recipients with a normal biopsy (n = 19), histological antibody-mediated damage (ABMR, n = 52) or interstitial fibrosis/tubular atrophy (IFTA, n = 47) following Banff 2015 and 2017 classification.

Direct SAB detected DSA in 13 patients missed by screening. Strategy 1 detected DSA in 0% normal, 61.5% ABMR and 8.5% IFTA patients; percentages with strategy 2 were 5.2%, 78.8% and 14.8% (p=0.004). Strategy 2 identified DSA allowing full ABMR diagnosis in 17% cases missed by strategy 1. Thereafter, direct SAB from manufacturer A confirmed DSA in 46% DSA-positive cases with strategy 2 (55.5% ABMR cases).

Conclusions

Luminex screening failed to identify clinically relevant HLA antibodies, hampering DSA detection in patients with possible ABMR. Direct SAB testing should be the chosen strategy for post-transplantation monitoring, albeit direct SAB from the two existing manufacturers may diverge in as much as 50% of cases.

中文翻译：

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Luminex筛选首次与直接单抗原珠试验的比较：肾脏移植后监测HLA抗体的不同策略。

主要问题

Luminex面板和单抗原珠（SAB）分别用于筛选和DSA特异性测定。SAB的成本可能会限制其一般用途，因此某些实验室仅在阳性筛选后才进行SAB测试。

方法

我们比较了两种策略：1）仅当使用制造商A的试剂盒进行阳性筛选时才进行SAB的检测； 2）直接指导制造商B的SAB进行检测，并将其敏感性与组织学发现相关联。

结果

根据Banff 2015年和2017年的分类，我们选择了118名活检正常，组织学抗体介导的损伤（ABMR，n = 52）或间质纤维化/肾小管萎缩（IFTA，n = 47）的肾移植受者。

直接SAB在筛查漏诊的13例患者中检测到DSA。策略1在0％正常，61.5％ABMR和8.5％IFTA患者中检测到DSA；策略2的百分比为5.2％，78.8％和14.8％（p = 0.004）。策略2确定了DSA，从而可以在策略1遗漏的17％病例中对ABMR进行全面诊断。此后，制造商A的直接SAB在策略2的46％DSA阳性病例（55.5％ABMR病例）中确认了DSA。

结论

Luminex筛查未能鉴定出临床相关的HLA抗体，从而妨碍了可能的ABMR患者的DSA检测。直接SAB测试应该是移植后监测的选择策略，尽管来自两家现有制造商的直接SAB可能会在多达50％的情况下出现差异。