The acute cytotoxicity of the first ten MEIC chemicals has been estimated by others in various cell lines. In the present investigation, isolated human polymorphonuclear leukocytes (PMN) from ten healthy non-smoking laboratory personnel were used to assess in vitro toxicity of the same chemicals. The cells were treated with different concentrations of the respective chemicals for three hours and their vitality and chemotaxis were tested. Vitality was measured by fluorescence microscopy after the addition of fluorescein diacetate and ethidium bromide. Living cells which took up and hydrolysed fluorescein diacetate, and dead cells, stained by ethidium bromide, were counted and the percentage of live cells was calculated. Locomotion stimulated by the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (F-MLP), was measured in blind-well Boyden chambers and a chemotactic index was calculated. The results were mathematically transformed to produce a linear curve, and then fitted by the linear least squares procedure, from which LC50 and IC50 values were obtained by interpolation. All the chemicals decreased the vitality and inhibited the chemotaxis of the PMN. Obviously the chemotactic test was more sensitive than the vitality one. A correlation (r = 0.933) was found between vitality and chemotaxis inhibition. Spearman rank correlation analysis revealed significant correlations between our results and those from in vitro experiments conducted in other laboratories, as well as with data concerning mouse, rat and human lethal doses.
Interaction between Chlamydia spp. and human polymorphonuclear leukocytes in vitro.