Contact hypersensitivity to disodium hexachloroplatinate in mice

Cross-reactivity between halogenated platinum salts in an immediate-type respiratory hypersensitivity model

Halogenated platinum salts can trigger the development of occupational asthma. Until recently, laboratory research into the development and manifestation of platinum hypersensitivity responses were hindered by the lack of an animal model suitable for assessing the functional consequences of allergic sensitization. We employed a newly developed mouse model to assess the potential allergenicity of ammonium tetrachloroplatinate (ATCP), compare the relative potency of ATCP and another platinum salt, ammonium hexachloroplatinate (AHCP) and assess potential cross-reactivity. Mice were topically sensitized with ATCP before being challenged by intratracheal aspiration (IA) with ATCP. Ventilatory responses were assessed using whole-body plethysmography (WBP). An immediate response (IR) was observed in ATCP-sensitized and challenged mice. Two days later, responsiveness to the nonspecific stimuli methacholine (Mch) was detected in ATCP-sensitized mice using WBP. Bronchoalveolar lavage fluid collected from sensitized mice contained an average of 3.3% eosinophils compared to less than 0.5% in non-sensitized mice (p<.05). Serum harvested from sensitized mice also contained increased total serum immunoglobulin E (p<.05). These data are the first to demonstrate that topical exposure to ATCP is sufficient to develop immediate type hypersensitivity and that a single intra-airway challenge is capable of triggering pulmonary responses. To investigate potential cross-reactivity, mice were sensitized to AHCP and, challenged by a single IA with a second platinum compound, ATCP. Compared to non-sensitized mice challenged with ATCP, these mice exhibited an IR, responsiveness to Mch, and eosinophilic infiltration in the lungs similar to that achieved with AHCP challenge, thus demonstrating cross-reactivity.

Lung function changes in mice sensitized to ammonium hexachloroplatinate

Occupational exposure to halogenated platinum salts can trigger the development of asthma. The risk to the general population that may result from the use of platinum in catalytic converters and its emerging use as a diesel fuel additive is unclear. To investigate pulmonary responses to platinum, we developed a mouse model of platinum hypersensitivity. Mice were sensitized through application of ammonium hexachloroplatinate (AHCP) to the shaved back on days 0, 5 and 19, and to each ear on days 10, 11 and 12. On days 24 and 29, mice were challenged by oropharyngeal aspiration with AHCP in saline. Before and immediately after challenge, pulmonary responses were assessed using whole body plethysmography (WBP). A dose-dependent increase in immediate responses was observed in AHCP-sensitized and challenged mice. On days 26 and 31, changes in ventilatory responses to methacholine (Mch) aerosol were assessed by WBP; dose-dependent increases in Mch responsiveness occurred in sensitized mice. Lymph node cell counts indicate a proliferative response in lymph nodes draining the sites of application. Bronchoalveolar lavage fluid harvested from sensitized mice contained an average of 5% eosinophils compared to less than 0.5% in non-sensitized mice (p < 0.05); significant increases in total serum immunoglobulin E were observed for all sensitized mice. Although a second airway challenge on day 29 affected some results, only one airway challenge was needed to observe changes in lung function.

Interleukin-1β expression in murine J774A.1 macrophages exposed to platinum compounds: The role of p38 and ERK 1/2 mitogen-activated protein kinases

Although skin and respiratory sensitizing properties of platinum compounds have been proved in humans and mice, little is known about signal transduction pathways leading to cytokine production in the induction phase. It is generally assumed that induction of skin sensitization, but not skin irritation, is associated with a rapid increase in the IL-1beta mRNA expression. In this study, IL-1beta expression and a role of mitogen-activated protein kinases (MAPKs) in this process were investigated in murine macrophages J774A.1 exposed to four platinum compounds. Potassium tetrachloroplatinate (K(2)PtCl(4); TCPP), ammonium tetrachloroplatinate ((NH(4))(2)PtCl(4); TCPA), ammonium hexachloroplatinate ((NH(4))(2)PtCl(6); HCPA) showed a very similar range of cytotoxic concentrations (IC(50) values: 238 microM+/-30; 269 microM+/-39 and 245 microM+/-31, respectively) as assessed in the 24-h MTT reduction test. Cytotoxicity of cis-diammineplatinum dichloride (cisplatin) was considerably higher (IC(50) of 23 microM+/-4). While increased expression of IL-1beta mRNA was observed in the macrophages exposed to each test compound, IL-1beta protein production was detected in cell lysates after treatment with TCPP, TCPA and HCPA for 24h (concentration range of 150-350 microM) as well as for 2h (450-650 microM). The treatment with each compound resulted in the phosphorylation of both p38 MAPK and ERK 1/2 (p44/42). Blocking the activation of p38 MAPK as well as ERK 1/2 with specific inhibitors (SB203580 and U0126, respectively) down-regulated the IL-1beta expression. Interestingly, the skin irritant sodium dodecyl sulfate did not trigger phosphorylation of these kinases, nor induced IL-1beta production. These data suggest that p38 MAPK and ERK 1/2 play an important role in induction of IL-1beta expression in J774A.1 macrophages exposed to test platinum compounds.

Platinum group elements in the environment and their health risk

Accumulation of platinum group elements (PGEs) in the environment has been increased over the time. Catalytic converters of modern vehicles are considered to be the main sources of PGE pollution, since the correlation is between the Pt:Rh ratios in various environmental compartments and in converter units. The present literature survey shows that the concentration of these metals has increased significantly in the last decades in diverse environmental matrices; like airborne particulate matter, soil, roadside dust and vegetation, river, coastal and oceanic environment. Generally, PGEs are referred to behave in an inert manner and to be immobile. However, there is an evidence of spread and bioaccumulation of these elements in the environment. Platinum content of road dusts can be soluble, consequently, it enters the waters, sediments, soil and finally, the food chain. The effect of chronic occupational exposure to Pt compounds is well-documented, and certain Pt species are known to exhibit allergenic potential. However, the toxicity of biologically available anthropogenic Pt is not clear. Hence, there is a need to study the effect on human health of long-term chronic exposure to low levels of Pt compounds.

Altered serum cytokine and immunoglobulin levels in the workers exposed to antimony

1 Antimony (Sb), an industrial and environmental toxicant, is known to cause dermatitis and pulmonary inflammations, but the immunomodulatory effects of environmental or occupational exposure to Sb have not been reported. To initiate investigation of Sb-induced alterations of the immune system, the concentrations of the IgG subclasses, IgE, interleukin-2, interferon-gamma, and interleukin-4 in sera obtained from workers exposed to Sb through antimony trioxide manufacture were determined and compared with those of control subjects. 2 The serum levels of IgG1, an immunoglobulin involved in host defense against many microbial infections, were significantly lower in the sera of Sb-exposed individuals than the controls. The serum concentrations of IgE, an immunoglobulin mediating allergic hypersensitivity, also were lower in the Sb-exposed workers than the controls. In addition, the levels of interleukin-2 and interferon-gamma, multifunctional cytokines for T-cell mediated immunity, were lowered in the factory workers. 3 A significant positive correlation between IgG4 and urine Sb levels was found among the Sb-exposed workers, indicating a possible role of IgG4 in Sb-mediated pulmonary or skin pathogenesis. 4 The present study provides the first report on immune alterations induced by occupational exposure to Sb and suggests that Sb exposure disturbs immunohomeostasis in humans observed as a function of aberrant serum cytokine and immunoglobulin levels, which could influence health.