Lymphocyte esterases and hydroxylases in neurotoxicology.

Certain human lymphocytic enzymes, such as neuropathy target esterase (NTE), have become useful markers in clinical toxicology. NTE has been proposed as a predictive marker in organophosphate poisoning for the subsequent development of organophosphate-induced delayed neuropathy. We studied lymphocyte aryl hydrocarbon hydroxylases, and using a differential method based on that of NTE employing a phenyl-alkanoic substrate, developed an enzyme assay for use in toxic neuropathies. The assayed enzyme, which we refer to as neuropathy target hydroxylase (NTH), performed similarly to NTE in the evaluation of coherent clinical data obtained in patients with toxic neuropathies. This study indicates good correlation between the severity of clinical illness and abnormally low levels of NTH in neuropathies of varied etiology. A simplified protocol for NTH assay is presented.