Systemic Immune Alterations

Recently, it has been shown that inhalation of MWNTs caused suppression of the systemic immunity without resulting in significant lung inflammation or tissue damage [82,83]. Inhaled MWNTs in fact modified the functionality of spleen cells in exposed mice [82]. Notably, the activity of cyclooxygenase (COX) enzymes in spleen was affected as a response to a cytokine (TGF(5) released from the lungs. This cytokine activated the COX pathway in the spleen, triggering T-cell dysfunction and systemic immunosuppression [83]. 

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Over the last decade, there has been a steady increase in the popularity and usage of natural products to enhance overall health. These nutraceuticals and functional foods modulate the function of various physiological systems including the immune system. By altering immunity, it is possible to augment an individual s ability to ward off infection, or suppress autoimmunity and chronic inflammatory diseases. Thus, the renaissance of herbal extracts as well as the increased consumption of other dietary components has afforded the public a relatively inexpensive way to self-medicate. 

While the database for developmental immunotoxicants is relatively modest, several chemicals have received considerable research attention. For example, Luebke et al. (2004), in a report to the USEPA, reviewed the comparative age-related sensitivities of the human and rodent immune systems for four developmental immunotoxicants DES, lead, diazepam, and tributyltin. These authors concluded that DES, a strong estrogenic compound, produced similar immune alterations at similar doses following exposure of adult rodents and embryos or neonates. However, the immune changes persisted following early exposure, whereas adults appeared to be able to recover post-exposure. 

As indicated by this brief overview there is considerable evidence for a close relationship between changes in the immune system and depression, particularly MDD. Whether there is a clear cause and effect relationship between these is not known in most cases, although there are sdrong data in the case of IL-6 and IFN-a, as noted. It will be important to determine more clearly the exact relationship between depression and immune system alterations. There is also a need to determine which of the immune alterations that are found are clinically important (Irwin, 2001). 

More recently it has become apparent that this relationship is reciprocal in nature, i.e., the immune system also can regulate the HPA axis and have significant effects on the CNS (see Carlson, 2003 Eskandari et al., 2003, for reviews). Chemo-kines, cytokines and other mediators released by the immune system can alter CNS function and abnormally high levels of some cytokines, such as IL-6, are associated with mental disorders, such as depression (see Chapter 34). In addition it is now clear that some neurohormones once thought to be exclusively neuronal are also produced by immune cells and that some immune system mediators are expressed by cells within the CNS. A consequence of this is that drugs whose primary site of action has classically been defined as the cen-... 

The toxic activity of the plant is unclear. Pokeweed mitogen (PWM) noted in the plant fluids may initiate changes in the immune system that alter T- and... 

Alters cellular mechanisms, enzyme systems, immune responses, collagen biosynthesis, suppressing synovitis of the active stage of rheumatoid arthritis. 

The mechanisms proposed by Rea, Bell, and Pall are not incompatible. Each addresses MCS from a different angle and all three are valid. Rea attributes MCS to a weakened immune system and altered metabolism. Bell proposes that neurosensitization is the key to MCS induction, and Pall theorizes a molecular biological explanation. There are differences, however. 

Data regarding the clinical presentation of CMV retinitis, pattern of infection, disease course, and complications have been obtained in the last two decades because of its association with AIDS. Therapy for AIDS has been greatly improved since the mid-1990s with the development and use of highly active antiretroviral therapy (HA ART). HA ART therapy improves systemic immune function in many patients with AIDS, and thus has drastically altered the incidence and clinical features of CMV retinitis and other opportunistic infections (4). 

HUMAN HEALTH RISKS Acute Risks irritation of eyes, mucous membranes, upper respiratory tract and skin gastrointestinal effects vomiting headaches pulmonary edema Chronic Risks effects on liver, eyes, kidneys, CNS and immune system may alter genetic material can cause male reproductive effects known carcinogen. 

CHRONIC HEALTH RISKS effects on the liver, kidneys, and cardiovascular system immune system effects severe eye and skin irritant mutagen may alter genetic materials possible human carcinogen. 

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