Use of proliferation tests to evaluate the effects of complexing agents on beryllium toxicity.

Occupational exposure to beryllium may cause chronic beryllium disease (CBD), a granulomatous interstitial pneumonitis caused by a cell-mediated immune response with delayed hypersensitivity initiated by an electrostatic interaction with the MHC class II human leukocyte antigen (HLA). Increased research efforts focus on the development of a CBD treatment by chelation therapy. This work presents an in vitro evaluation of the beneficial effects of beryllium chelation with different organic substrates. We have used a standard beryllium lymphocyte proliferation test (BeLPT) adapted for mouse splenocytes. Three complexing agents, 4,5-dihydroxy-1,3-benzenedisulfonic acid (tiron), nitrilotripropionic acid (NTP) and nitrilotriacetic acid (NTA), were tested using different protocols of the splenocyte proliferation test (SPT). We studied their corrective effect (beryllium pre-exposed splenocytes), their protective effect (ligand pre-exposed splenocytes) and their combined effects at fixed Be:L ratio of 1:2, at fixed Be concentration and at fixed L concentration. We also studied the effect of tiron in preventing splenocyte sensitization to beryllium. All three complexing agents showed a corrective effect and proved efficient in the combined effects, except NTA in the fixed Be:L ratio. Only NTP and tiron showed a significant protection at lower beryllium concentrations, while NTA was not significant. Splenocytes pre-exposed to chelated beryllium did not show sensitization while splenocytes pre-exposed to beryllium were sensitized. We observed a strong correlation between the efficiency of the complexing agent and its affinity towards beryllium. Both tiron and NTP showed a similar affinity towards the beryllium ion that is 10(7) higher than that of NTA.

Determination of alkali-labile phosphoprotein phosphorus from fish plasma using the Tb(3+)-tiron complex as a fluorescence probe.

A sensitive method based on the fluorescence quenching effect of the Tb(3+)-Tiron complex is proposed for the determination of alkali-labile phosphoprotein phosphorus (ALP) released from fish plasma. The detection limit was 5.4 ng/ml (S/N = 2), and the relative standard deviation of the quenching effect (6 replicates) was 4.6%. The results obtained by the proposed method were in good agreement with those obtained by the colorimetric assay. The advantages of the present method are its relatively simple detection procedure, the lack of toxic organic solvents, and high sensitivity.