Purpose of Review

Mast cell (MC) activation syndromes (MCAS) are conditions defined by recurrent episodes of severe systemic anaphylaxis or similar systemic events triggered by MC-derived mediators that can be measured in biological fluids. Since some symptoms of MC activation may occur due to other, non-MC etiologies and lead to confusion over diagnosis, it is of crucial importance to document the involvement of MC and their products in the patients´ symptomatology.

Recent Findings

The most specific and generally accepted marker of severe systemic MC activation is an event-related, transient increase in the serum tryptase level over the individual baseline of the affected individual. However, baseline concentrations of serum tryptase vary among donors, depending on the genetic background, age, kidney function, and underlying disease. As a result, it is of critical importance to provide a flexible equation that defines the diagnostic increase in tryptase qualifying as MCAS criterion in all patients, all situations, and all ranges of baseline serum tryptase. In 2012, the consensus group proposed the 120% + 2 ng/ml formula, which covers the great majority of groups, including cases with low, normal, or elevated basal serum tryptase level.

Summary

This formula has been validated in subsequent studies and has proven to be a robust and consistent diagnostic criterion of MCAS. The present article is discussing the impact of this formula and possible limitations as well as alternative markers and mediators that may be indicative of MCAS.

中文翻译：

---

类胰蛋白酶相对于个体基线的可逆性升高：为什么它是严重全身性肥大细胞激活和 MCAS 的最佳生物标志物？

审查目的

肥大细胞 (MC) 激活综合征 (MCAS) 是指反复发作的严重全身性过敏反应或由 MC 衍生介质引发的类似全身性事件，可在生物体液中进行测量。由于 MC 激活的某些症状可能是由其他非 MC 病因引起的，并导致诊断混乱，因此记录 MC 及其产物与患者症状的关系至关重要。

最近的发现

严重全身性 MC 激活的最具体且普遍接受的标志是与事件相关的、受影响个体的血清类胰蛋白酶水平短暂升高。然而，血清类胰蛋白酶的基线浓度因捐赠者而异，具体取决于遗传背景、年龄、肾功能和潜在疾病。因此，提供一个灵活的方程来定义所有患者、所有情况和所有基线血清类胰蛋白酶范围内符合 MCAS 标准的类胰蛋白酶诊断性增加是至关重要的。 2012年，共识小组提出了120%+2ng/ml公式，涵盖了绝大多数群体，包括基础血清类胰蛋白酶水平低、正常或升高的病例。

概括

该公式在后续研究中得到验证，被证明是稳健且一致的MCAS诊断标准。本文正在讨论该公式的影响和可能的局限性以及可能指示 MCAS 的替代标记物和介质。