Motorcycle exhaust particles augment antigen-induced airway inflammation in BALB/c mice

Evidence indicates that environment pollutants from fossil fuel combustion compromise the immune system by enhancing allergic reactions and damaging the respiratory tract. This study was performed to investigate the effects of motorcycle exhaust particles (MEP), a major air pollutant especially in the urban areas of Taiwan, on allergen-induced airway inflammatory reactions in lab animals. BALB/c mice were intratracheally instilled with ovalbumin (OVA), MEP, or phosphate-buffered saline, 3 times every 2 wk. Airway hyperresponsiveness was measured in unrestrained mice by barometric plethsmography. Bronchoalveolar lavage fluid (BALF) and serum from treated animals were collected for cytokine and antibody determination by enzyme-linked immunosorbent assay (ELISA). Lung tissue stained with hematoxylin/eosin was examined. Data showed that MEP augmented OVA-induced airway inflammation; characterized by infiltration of eosinophils and neutrophils in BALF and lung tissue inflammation. The combination of OVA and MEP markedly increased interleukin-4 (IL-4), interleukin-5 (IL-5), and tumor necrosis factor-alpha (TNF-alpha) protein levels in BALF. In addition, MEP also augmented OVA-induced rise in OVA-specific immunoglobulin (Ig) G1 and IgE and airway hyperresponsiveness. Pretreated lavage cells with mitogen-activated protein kinase (MAPK) inhibitors showed that TNF-alpha release was significantly inhibited. This study found that MEP augmented antigen-induced allergic airway inflammation and airway hyperresponsiveness through a Th2-dominant pathway.

Effect of horse gram lectin (Dolichos biflorus agglutinin) on degranulation of mast cells and basophils of atopic subjects: identification as an allergen

Horse gram (Dolichos biflorus) is widely consumed in the tropical south Asian countries including rural areas of India. Since D. biflorus agglutinin (DBA) is an important dietary lectin in horse gram, we have studied its effect on the degranulation of mast cells and basophils of atopic subjects. Allergy to horse gram lectin has not been reported so far. Skin prick test (SPT) was performed with 100 microg/mL of DBA. DBA-specific IgE was detected by dot-blot, and ELISA. Histamine release (HR) assay was carried out using leukocytes from non-atopic and atopic subjects, and rat peritoneal exudate cells. Among the atopic group, 10 of 48 subjects (21%) were found to be positive for DBA by SPT, and none were positive in the non-atopic group (n=20). Two subjects out of the ten who tested positive for DBA by SPT were found to be sensitized to DBA as revealed by the presence of specific IgE by ELISA and dot-blot. The HR was found to be 2- to 3-fold higher in DBA-allergic subjects than in non-atopic and atopic subjects. Basophil HR by DBA was found to be similar in both non-atopic and atopic subjects. However, DBA induces activation of mast cells in vivo in a sub-population (21%) of atopic subjects. Two subjects have been identified as having food allergy to horse gram based on the presence of DBA-specific IgE with a positive correlation to basophil HR. This is the first report of food allergy to horse gram, and DBA has been identified as an allergen.