Immune system location

Apart from the wide range of neurotoxic and behavioral effects caused by OPs, many of which can be related to inhibition of AChE, other symptoms of toxicity have been reported. These include effects on the immune system of rodents (Galloway and Handy 2003), and effects on fish reproduction (Cook et al. 2005 Sebire et al. 2008). In these examples, the site of action of the chemicals is not identified. Indirect effects on the immune system or on reproduction following initial interaction with AChE of the nervous system cannot be ruled out. It is also possible that OPs act directly on the endocrine system or the reproductive system, and phosphorylate other targets in these locations (Galloway and Handy 2003). 

Table 9.5 The major cellular sources of human TNF-p. As is evident, TNF-a synthesis is not restricted to cells of the immune system, but is undertaken by a wide variety of different cells in different anatomical locations, including the brain...

Immunological Effects. No data on immunotoxicity of mirex in were located. The only information about the immunological effects of mirex exposure in animals was provided by one acute oral study in rats in which decrease spleen weight was reported (Buelke-Sam et al. 1983). Thus, it is uncertain whether persons exposed to mirex at hazardous waste sites might experience adverse effects on the immune system. 

No studies were located that examined the immunotoxicity of mirex in experimental animals. The information available from one acute study in rats indicates that the immune system is not a target of... 

Immunotoxicity. No information was located on the immunological effects of bromomethane in humans or animals exposed by any route. A battery of immune function tests in several animal species exposed to bromomethane by the inhalation and the oral routes would be valuable in determining if the immune system is adversely affected, and if so, in determining species and route specificity, as well as the threshold for those effects. 

Clearly, further studies will be necessary to sort out the multiple factors involved in the in vivo immune response to C. neoformans carbohydrate-mimetic peptides. Several conclusions may be drawn from the results to date. Peptides that mimic the cryptococcal capsular polysaccharide show specificity, in that each peptide binds with differing affinity to closely related mAbs [140,149]. The pattern of binding to protective and nonprotective mAbs differs between the mimetic peptides and the polysaccharide [140]. Protective efficacy is related to the location of carbohydrate epitopes recognized by these mAbs, within the polysaccharide capsule, but hkely also depends on interactions between mAbs and cellular responses [149]. Peptides have been shown to be functional, immunogenic mimics, but their protective efficacy depends on multiple factors, including the type of Abs elicited and interactions with the cellular immune system. Protective efficacy does not correlate with binding affinity to representative mAbs, but rather depends on the nature of these interactions. 

Immunotoxicity. No studies were located assessing the potential effect on the immime system during 3,3 -dichlorobenzidine exposure. Studies that examine antibody levels and responses to bacterial infections after exposure to 3,3 -dichlorobenzidine would provide valuable information on the immune system. Also, evaluation of morbidity among individuals exposed to 3,3 -dichlorobenzidine in the workplace may provide important indirect evidence regarding their immime status. 

The immune system is complex, as it is not confined to one or several organs, but rather spread throughout the body. In addition, it involves delicate interactions between different cell types that vary not only between different locations but also in space and time after a toxic or pathologic insult. The various types of immunotoxicity differ considerably in the complexity of the mechanisms they affect. Therefore, also the phase of development of in vitro testing differs considerably between the various types of immunotoxicity. 

Dermal Effects. No studies were located regarding dermal effects in humans following inhalation exposure. However, contact dermatitis in persons exposed to nickel compounds is one of the most common effects of nickel exposure (see Section 2.2.3.2). In addition, immunological studies indicate that the dermatitis is an allergic response to nickel, and significant effects on the immune system have been noted in workers exposed to nickel (see Section 2.2.1.3). 

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