The Allergen-Specific IgE Concentration Is Important for Optimal Histamine Release From Passively Sensitized Basophils

BACKGROUND: The basophil histamine release (HR) assay can be used for allergy diagnosis in addition to the conventional measurement of allergen-specific IgE (sIgE). Passive sensitization of basophils increases the versatility and allows testing the biological relevance of allergen-induced IgE cross-linking in any serum unbiased by the cellular component. However, not all the patient sera perform equally well and we hypothesized that the absolute level and fraction of sIgE affect the performance. Choosing birch pollen allergy as a model, we investigated the concentration of sIgE needed for successful passive sensitization using soluble- or matrix-fixed Bet v 1. METHODS: Twenty-eight sera with Bet v 1 sIgE [7 sera within each allergy class (1: 0.1–0.70 kUA/L, 2: 0.71–3.50 kUA/L, 3: 3.51–17.50 kUA/L, and 4+: >17.50 kUA/L)] and a negative control serum pool were used to passively sensitize donor basophils, obtained from buffy coat blood (n = 3). The cells were incubated (30 min) with a soluble allergen (rBet v 1 from 0.2 to 50 ng/ml), matrix-fixed allergen (ImmunoCAP™ containing recombinant Bet v 1), or phorbol 12-myristate 13-acetate (PMA)/ionomycin mixture (maximal HR) and released histamine was quantified fluorometrically. RESULTS: The lowest level of Bet v 1 sIgE generating a detectable HR (HR > 10% of maximal release) in all the 3 runs was found to be 1.25 kUA/L (corresponding to allergy class 2, 0.71–3.50 kUA/L). Furthermore, sera from allergy classes 3 and 4+ ascertained a significant reproducible HR: 42/42 vs. 5/21 in allergy class 1 and 15/21 in allergy class 2. Using ImmunoCAP™s containing Bet v 1 as a matrix-fixed allergen system, similar results were obtained where the lowest sIgE concentration mediating an HR was 1.68 kUA/L and 7/7 for both allergy classes 3 and 4+. CONCLUSION: The results demonstrate that the IgE titer is strikingly robust in predicting the ability to sensitize basophils and produce a measurable HR

Introduction of Mercury-Free Gold Extraction to Small-Scale Miners in the Cabo Delgado Province in Mozambique

Background. The majority of small-scale gold miners worldwide, including those in Mozambique, use mercury to extract gold. Over the last fifty years, gold production from small-scale mining has been accelerating and consequently the amount of mercury released to the environment has increased dramatically, causing major global health problems. In 2018, a team from the Danish non-governmental organization Diálogos introduced the mercury-free gold extraction method in the Cabo Delgado province in Mozambique in the villages of Waqueia and Nanlia. Objectives. The objective of this project was to teach local miners this method to reduce mercury pollution. An additional objective was to compare the local gold extraction method and the mercury-free gold extraction method in terms of gold recovery. The hypothesis was that the level of gold recovery would be higher with the mercury-free method compared to the locally used amalgamation method. Materials and Methods. An experimental study comparing the two gold extraction methods was carried out where local miners processed gold-bearing ore using their standard procedures with the amalgamation method and the Diálogos team processed an equivalent amount of gold-bearing ore with the mercury-free gold extraction method. The tests were carried out once at each mining site. Results. Under even circumstances in a controlled setting, the mercury-free method yielded up to 78% more gold than the amalgamation method normally used by the miners. Conclusions. The strengths of the mercury-free gold extraction method include low costs, higher gold yield, benign environmental impact, legality and needed chemicals are more readily available compared with the amalgamation method. However, the mercury-free method may be more time consuming than the amalgamation method, especially for beginners. Borax is typically available in developed urban areas, as it is commonly used in the welding industry and by jewelers, but can be hard to find in more remote villages. Competing Interests. The authors declare no competing financial interests