On the long-term effects of methyl isocyanate on cell-mediated immunity in Bhopal gas-exposed long-term survivors and their offspring.

Methyl isocyanate (MIC) is a toxic industrial chemical that is documented as a potent respiratory toxicant. We investigated cell-mediated immunity (CMI) in the MIC-exposed long-term survivors and their offspring born after the Bhopal gas-leak tragedy in 1984. Several earlier reports show inconsistency in the assessment of immunological effects of MIC on the human population. In these studies, important factors including lifestyle attributes were overlooked. We incorporated these factors also in our study of the basic cell-mediated immune function in the Bhopal MIC-affected population. Twenty-seven years after exposure, we assessed the circulating T-lymphocyte frequency using E-Rosette assay. A total of 46 MIC-exposed healthy long-term survivors and their offspring were studied vis-a-vis parallel gender-age group-matched unexposed controls from Bhopal and various other regions of India. The influence of several lifestyle variabilities (smoking, alcohol intake, and tobacco chewing) on T-lymphocyte frequency was also taken into consideration. Our observations suggest that Erythrocyte-Rosette-forming cell (E-RFC) distribution frequency is largely insignificant in the MIC-affected population as compared to controls ( p > 0.05). In the MIC-affected tobacco chewers, there was a trend of suppression in CMI (relative decrease = 10.3%) as compared to nonchewers. Overall, our results show negligible long-term effect of MIC on CMI measured in terms of E-RFC frequency. These observations are not in agreement with earlier findings that immunosuppressive effects of MIC exposure persist in the T-cells of the affected population. However, atypical lymphocytes were frequently observed as E-RFC in the exposed females when compared to all other subgroups. Hematopoietic disorders (atypical lymphocytosis) in the MIC-affected population along with previous reports on the cytogenetic and humoral immune system linking cancer risk and chronic obstructive pulmonary disease (COPD) are important.

Mustard Gas Inhalation Injury: Therapeutic Strategy.

Mustard gas (sulfur mustard [SM], bis-[2-chloroethyl] sulfide) is a vesicating chemical warfare agent and a potential chemical terrorism agent. Exposure of SM causes debilitating skin blisters (vesication) and injury to the eyes and the respiratory tract; of these, the respiratory injury, if severe, may even be fatal. Therefore, developing an effective therapeutic strategy to protect against SM-induced respiratory injury is an urgent priority of not only the US military but also the civilian antiterrorism agencies, for example, the Homeland Security. Toward developing a respiratory medical countermeasure for SM, four different classes of therapeutic compounds have been evaluated in the past: anti-inflammatory compounds, antioxidants, protease inhibitors and antiapoptotic compounds. This review examines all of these different options; however, it suggests that preventing cell death by inhibiting apoptosis seems to be a compelling strategy but possibly dependent on adjunct therapies using the other drugs, that is, anti-inflammatory, antioxidant, and protease inhibitor compounds.

N-acetyl-L-cysteine protects against inhaled sulfur mustard poisoning in the large swine.

CONTEXT: Sulfur mustard is a blister agent that can cause death by pulmonary damage. There is currently no effective treatment. N-acetyl-L-cysteine (NAC) has mucolytic and antioxidant actions and is an important pre-cursor of cellular glutathione synthesis. These actions may have potential to reduce mustard-induced lung injury. OBJECTIVE: Evaluate the effect of nebulised NAC as a post-exposure treatment for inhaled sulfur mustard in a large animal model. MATERIALS AND METHODS: Fourteen anesthetized, surgically prepared pigs were exposed to sulfur mustard vapor (100 µg.kg⁻¹), 10 min) and monitored, spontaneously breathing, to 12 h. Control animals had no further intervention (n = 6). Animals in the treatment group were administered multiple inhaled doses of NAC (1 ml of 200 mg.ml⁻¹ Mucomyst™ at + 30 min, 2, 4, 6, 8, and 10 h post-exposure, n = 8). Cardiovascular and respiratory parameters were recorded. Arterial blood was collected for blood gas analysis while blood and bronchoalveolar lavage fluid were collected for hematology and inflammatory cell analysis. Urine was collected to detect a sulfur mustard breakdown product. Lung tissue samples were taken for histopathological and post-experimental analyses. RESULTS: Five of six sulfur mustard-exposed animals survived to 12 h. Arterial blood oxygenation (PaO2) and saturation levels were significantly decreased at 12 h. Arterial blood carbon dioxide (PaCO2) significantly increased, and arterial blood pH and bicarbonate (HCO3⁻) significantly decreased at 12 h. Shunt fraction was significantly increased at 12 h. In the NAC-treated group all animals survived to 12 h (n = 8). There was significantly improved arterial blood oxygen saturation, HCO3⁻ levels, and shunt fraction compared to those of the sulfur mustard controls. There were significantly fewer neutrophils and lower concentrations of protein in lavage compared to sulfur mustard controls. DISCUSSION: NAC's mucolytic and antioxidant properties may be responsible for the beneficial effects seen, improving clinically relevant physiological indices affected by sulfur mustard exposure. CONCLUSION: Beneficial effects of nebulized NAC were apparent following inhaled sulfur mustard exposure. Further therapeutic benefit may result from a combination therapy approach.

[Pharmacological correction of nonspecific resistance and production of proinflammatory cytokines during chronic intoxication with organophosphorus compound VX].

It is established in experiments on noninbred rats that the use of imunofan (20 mg/kg daily) and polyoxidonium (150 mg/kg daily) for 7 days on the background of chronic intoxication with organophosphorus agent VX (0.01 LD50, single daily treatment for 30 days) resulted in almost complete recovery of phagocytic-metabolic activity of neutrophils, the content of lysozyme, cationic protein of platelet, and levels of proinflammatory cytokines TNFa, IL-1b and IL-6 in the blood. The administration of T-activin (20 mg/kg daily for 7 days) restores these parameters insignificantly. The maximum overall stimulatory effect was produced by polyoxidonium, while the minimum effect was observed for T-activin.

The antibody response to methyl isocyanate: experimental and clinical findings.

Sera from 99 subjects exposed to the industrial gas leak in Bhopal on December 2, 1984 were studied along with sera from guinea pigs exposed to methyl isocyanate (MIC) to determine the production of antibodies specific to (MIC). Each of the four guinea pigs injected with the reactive isocyanate produced MIC-specific antibodies in titres of 1:5120 to 1:10240, when tested with MIC-guinea pig albumin antigen conjugate. Analogous antigens prepared by reaction of MIC with human serum albumin were used to probe production of antibodies in 264 serially obtained human sera from 99 subjects from Bhopal. MIC-specific antibodies belonging to IgG, IgM and IgE classes were detected in eleven subjects. Though titres were low and transient (declining after several months) these findings indicate that the single large exposure to MIC resulted in an immunologic response. This finding was concomitant with chronic respiratory effects following MIC exposure.

Effects of Nocardia rubra cell wall skeleton on interleukin 2 production and lymphocyte proliferation in former poison gas factory workers.

Phytohemagglutinin (PHA)-induced interleukin 2 (IL-2) production and lymphocyte proliferation were measured in former workers of the Okunojima Poison Gas Factory (poison gas workers), who have a high incidence of lung cancer, and the efficacy of administration of Nocardia rubra cell wall skeleton (N-CWS) was studied. In comparison with normal controls and poison gas workers receiving N-CWS, lymphocyte proliferation in poison gas workers not receiving N-CWS showed a significant decrease, while IL-2 production showed a slight though not statistically significant decrease. When N-CWS was administered to poison gas workers, IL-2 production and lymphocyte proliferation were significantly elevated, with a peak two weeks after administration. N-CWS, by elevating IL-2 production of lymphocytes, is considered to have improved the depression of lymphocyte proliferation.

Effects of Nocardia rubra cell wall skeleton on lymphocyte subsets in former poison gas factory workers.

Peripheral blood lymphocyte subsets were determined in former workers of the Okunojima Poison Gas Factory (poison gas workers) having a high incidence of lung cancer, and the effect of administration of Nocardia rubra cell wall skeleton (N-CWS) was studied. In poison gas workers not receiving N-CWS, both the percentage and absolute number of Leu-2a+ cells were significantly increased as compared with normal controls, while both the percentage and absolute number of Leu-7+ cells as well as the Leu-3a/Leu-2a ratio were significantly decreased. In poison gas workers receiving N-CWS, the percentage of Leu-2a+ cells was significantly decreased when compared with poison gas workers not receiving N-CWS, while the percentage of Leu-1+ cells and both the percentage and absolute number of Leu-7+ cells as well as the Leu-3a/Leu-2a ratio were significantly increased. When N-CWS was administered to poison gas workers, the percentage of Leu-2a+ cells significantly decreased, with a minimum two weeks after administration, while the percentage of Leu-3a+ and the Leu-3a/Leu-2a ratio significantly increased and the percentages of Leu-1+ and Leu-7+ cells also increased. Furthermore, the absolute number of Leu-3a+ cells increased markedly with a peak two weeks after administration. The absolute numbers of both Leu-1+ cells and Leu-7+ cells as well as total lymphocytes also significantly increased, but that of Leu-2a+ cells showed hardly any change. It is considered that a single administration of N-CWS transiently corrects the abnormality of lymphocyte subsets, and that repeated administration of N-CWS once every three months may maintain the lymphocyte subsets of poison gas workers at normal levels.