Environmental Engineering Reference
In-Depth Information
Aeroallergens
Sensitizer
IL-10(produces
moreT H 2 cells)
Chronic asthma
Macrophage
CD 23 +
Prolonged
muscle
contraction
Class II HC
IL-1
Leukomeres
Increased
bronchial hyper-
responsiveness
Eosinophil
IL-5,IL-3,GM-CSF
(activate, prolong survival)
(Attract)RANTES
IL-1
IL-6
2CD 4 T H 2 cell
Text
Chemotactic
factors(attract)
Bronchial and
epithelial damage
II-4
IL-13
Major basic protein
Cationic protein
Specific
IgE
Mast cell
B cell
Reactive oxygen intermediates
Nitric oxide
Leukotrienes
Platelet-activating factor
Histamine
Prostaglandin D 2
Leukotrienes
Cytotoxicity
smooth muscle
contraction
Bronchial smooth
muscle contraction
Serum le ak age from
blood vessels
Mucus secretion
Nerve irritation cough
Prolonged smooth
muscle contraction
Increased bronchial
hyperresponsiveness
serum leakage
Acute
asthma
FIGURE 23.16  Major immunologic pathways related to IgE-mediated immune responses. Same pathways
apply to allergens deposited in the nose. Pink-shaded areas deine (approximately) pathways inluenced by die-
sel PM. See reference for detailed explanation and references [323,324] for an additional summary related to
details of cytokine network and allergic effects. (Adapted from Pandya, R.J. et al., Environ. Health Perspect .,
110(Suppl. 1), 103, 2002.)
environmental antigens [112]. The details of the molecular pathways that regulate Th-1/Th-2
balance have been summarized in detail by Nel [114,115].
23.5  HUMAN HEALTH EFFECTS ASSOCIATED WITH AMBIENT PM
This section summarizes an enormous body of data on the health effects that have been asso-
ciated with ambient aerosols. Of necessity, the section is selective and limits itself to health
effects related to PM that results from the activities of man. The emphasis is on data derived
from epidemiological studies, but clinical or controlled exposures studies are cited when they
serve to buttress or refute data from larger epidemiological studies. A few issues that transcend
a speciic consideration of speciic health effects are presented prior to a more detailed discus-
sion of health effects.
23.5.1  g eneral  i ntroduction
Relationship between studies of mechanisms and studies of human health effects : Although many
of the studies on the molecular and cellular mechanisms relate speciic components of the ambi-
ent aerosol to speciic mechanistic pathways, such clarity is not possible in observational studies
of humans that are the principal sources of data on human health effects. In these studies, sub-
jects are exposed to a “chemical soup” that arises from multiple indoor and outdoor sources of
anthropogenic PM aerosol that have changing source contributions over short and long timescales
 
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