I. Bonilla

Specific Allergens Enhance Elastase Release in Stimulated Neutrophils from Asthmatic Patients

Background: The presence of the three forms of IgE receptor – the heterotrimeric high-affinity receptor for IgE (FcΕRI), the low-affinity receptor for IgE (FcΕRII/CD23) and the Mac-2/IgE-binding protein (ΕBP) – has been demonstrated on human neutrophils. We have previously shown that specific allergens are able to activate functional responses by neutrophils from allergic patients sensitized to those allergens. Neutrophils are present at the sites of allergic inflammation. The primary (azurophilic) granules of neutrophils contain a variety of enzymes, such as elastase, that might potentiate inflammation. It is not known whether specific allergens are able to elicit elastase release by neutrophils from allergic patients. In addition, we attempted to evaluate the relationship between neutrophil degranulation and lung function of the patients, measured as FEV1. Methods: Neutrophils were challenged in vitro with the specific allergens that produced clinical symptoms in asthmatic patients. The cells were also challenged with allergen to which the patients were not sensitive. Neutrophils from normal subjects were challenged with allergens as control. Results: The in vitro challenge of neutrophils with allergens to which the patients were sensitive elicited a release of elastase by these cells. The in vitro activation of neutrophils was highly allergen specific; allergens other than those accounting for clinical symptoms did not evoke elastase release, and allergens were ineffective on neutrophils from healthy donors. A significant inverse correlation was observed between elastase release and patients’ lung function, measured as FEV1. Conclusion: An IgE-dependent mechanism might promote elastase release by neutrophils at allergic sites. There is a significant inverse relationship between levels of elastase released by neutrophils from allergic patients and lung function, as assessed by FEV1.

Respiratory Burst in Neutrophils from Asthmatic Patients

Background: The role of oxygen radicals has been implicated in disease processes of asthma. We have previously shown that specific allergens were able to activate respiratory burst by neutrophils from allergic patients sensitized to allergens of the same type as those which produce clinical allergy. Objectives: In this study, we attempted to evaluate the production of respiratory burst by an anti-IgE Ab in neutrophils from asthmatic allergic patients (with and without immunotherapy treatment) and in neutrophils from healthy subjects. Method: Neutrophils were stimulated by 10 µg/mL of anti-IgE Ab for 15 min at 37°C. The production of respiratory burst from neutrophils was assayed by luminol-amplified chemiluminescence method. Results: The respiratory burst was significantly higher in neutrophils from non-IT-asthmatic patients than in neutrophils from both healthy (p<0.001) and IT-asthmatic (p<0.001) groups. The IT-asthmatic group presented levels of respiratory burst approximately equal to those from non-allergic subjects (p=0.426). Conclusions: We conclude that neutrophils obtained from allergic asthmatic patients have an increased propensity to generate respiratory bursts, in comparison with neutrophils from healthy subjects. Immunotherapy actively modifies the respiratory burst by neutrophils from allergic asthmatic patients.

Myeloperoxidase release after allergen-specific conjunctival challenge

Background: Allergen‐specific conjunctival challenge is a fruitful and complete tool in evaluating pathophysiological phenomena of allergic inflammation. After challenge, a significant neutrophil infiltrate occurred in allergic subjects. The primary (azurophilic) granules of neutrophils contain a variety of enzymes that might potentiate inflammation, such as myeloperoxidase (MPO). It is not known whether allergen‐specific conjunctival challenge (ASCC) is able to elicit MPO release. We also investigated the possible role of immunotherapy (IT) in the release of MPO. Method: The groups studied included Dactylis glomerata‐sensitive adult atopic patients suffering from seasonal allergic rhinoconjunctivitis, and healthy adult nonatopic volunteer controls. One group of allergic patients received no specific hyposensitization (not‐IT allergic group). A second group of allergic patients had been immunotherapy‐treated with Dactylis glomerata extract for the preceding three years and continued to receive a maintenance dose within the highest potency of the extract (IT‐allergic group). ASCC with Dactylis glomerata was performed outside the pollen season in all subjects. Myeloperoxidase was assayed by MPO‐enzyme immunoassay method. Results: Thirty minutes after challenge, myeloperoxidase levels in the non‐immunotherapy allergic patients were significantly higher compared than in the healthy group (p < 0.001). The levels of myeloperoxidase released in the immunotherapy allergic group were significantly lower than those in the nonimmunotherapy allergic group (p < 0.001) and higher than those in non‐allergic subjects (p < 0.001). Conclusion: These results indicate that after ASCC there is a release of MPO. Our study suggests that immunotherapy actively modifies the release of MPO after ASCC.

Ige-mediated downregulation of L-selectin (CD62L) on lymphocytes from asthmatic patients

Background: L‐selectin (CD62L) mediates the binding of lymphocytes to high endothelial venules of peripheral lymph nodes and is also involved in leukocyte attachment to the endothelium at sites of inflammation. Although it has been demonstrated that L‐selectin is shed after lymphocyte activation, it is unknown whether the expression of L‐selectin on the surface of lymphocytes can be modulated by an IgE‐dependent mechanism or whether immunotherapy (IT) might affect this mechanism.

Allergen-dependent CD14 modulation and apoptosis in monocytes from allergic patients.

Background: CD14 is a most important monocyte surface molecule. Recently, it has been reported that there is an important relationship between CD14 and immunoglobulin E, and that regulation of CD14 expression is an effector mechanism mediating apoptosis of monocytes.