Reduction of increased serum neutrophil chemotactic activity following effective hyposensitization in house dust mite allergy

Allergic rhinitis: past, present and the future

Allergic rhinitis represents a global health issue affecting between 10% to 25% of the world population, with increasing prevalence over the last decade. Although often trivialized by patients and doctors, allergic rhinitis is a significant cause of morbidity, in addition to its substantial economic impact. While allergic rhinitis is an inflammatory disorder of the upper airways, inflammation alone is insufficient to explain the chronic nature of the disease. An exciting concept which has recently emerged in asthma concerns the role of the bronchial epithelium as a key regulator of airway inflammatory and remodelling responses in asthma. It has been shown by our group that the disruption and alteration in the function of the lower airway epithelium in asthma leads to the generation of a variety of stimuli that lead to the restructuring of the airway wall. This raises interesting questions regarding a similar role for the upper airway epithelium in allergic rhinitis. This review aims to interpret past and current research into allergic rhinitis, and to address specific areas where future research is warranted, particularly in relation to the possibility of an altered upper airway epithelial phenotype in allergic rhinitis.

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 microg/mL of anti-IgE Ab for 15 min at 37 degrees 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.

New insights into the mechanisms of immunotherapy

Allergen-specific immunotherapy retains a place in treatment in patients with allergic rhinitis who fail to respond to conventional treatment with antihistamines and topical corticosteroids. Studies on mechanisms of immunotherapy have previously focussed on changes in serum antibodies, including blunting of seasonal rises in specific IgE and increase in "blocking" specific IgG antibodies. Immunotherapy in patients with rhinitis has also been shown to inhibit effector cells with a decrease in nasal mucosal eosinophils and epithelial mast cells. Recent evidence suggests that these events may be orchestrated by an effect of immunotherapy on T lymphocytes with alteration from a predominant "Th2" response (interleukin 4 and 5) in favour of an additional "Th1" response (gamma interferon) which may decrease tissue eosinophilia and local IgE production. Novel therapeutic approaches to allergic diseases might include use of topical gamma interferon, immunosuppressive agents, anti-CD4 antibodies or strategies directed specifically against IL-4 or IL-5.

Influence of grass pollen immunotherapy on cellular infiltration and cytokine mRNA expression during allergen-induced late-phase cutaneous responses

We have studied the influence of grass pollen immunotherapy on cellular infiltration and cytokine mRNA expression during allergen-induced late-phase cutaneous responses. In a double-blind, placebo-controlled trial of immunotherapy in 40 adult hay fever sufferers, clinical improvement was accompanied by a decrease in the size of the late-phase skin response. When the immunotherapy-treated group was compared with the placebo group, analysis of skin biopsies obtained 24 h after intradermal allergen revealed a significant reduction in the number of infiltrating CD3+ (P = 0.04) and CD4+ (P = 0.009) cells and a trend for a decrease in EG2+ eosinophils (P = 0.08). Treatment did not influence allergen-induced recruitment of CD8+ cells, neutrophils, or macrophages. Unexpected increases in expression of CD25 (P = 0.006) and HLA-DR (P = 0.007) were observed in the actively treated group. In situ hybridization using a panel of riboprobes demonstrated "TH2-type" (IL-4, IL-5) cytokine mRNA responses in both groups of patients. In contrast, significant hybridization for IL-2 (8/16 patients, P = 0.02) and for interferon-gamma (6/16 patients, P = 0.04) was observed only in the actively treated group. These findings indicate that immunotherapy is associated with suppression of allergen-induced CD4+ T lymphocyte infiltration, but among the cells that are recruited, there is upregulation of CD25 and HLA-DR. At least in this model, immunotherapy does not appear to affect expression of TH2-pattern cytokines in response to allergen exposure, but expression of mRNA for Th1-type cytokines was enhanced in half of the patients. The results support the view that immunotherapy may possibly be working through induction of T cell tolerance.

The effect of immunotherapy on interleukin-1 and tumor necrosis factor production of monocytes in asthmatic children

A longitudinal study was conducted to determine the pathogenesis and effect of immunotherapy (IT) on monocyte function. Production of interleukin-1 (IL-1) and tumor necrosis factor (TNF) by peripheral blood monocytes in 31 asthmatic children before and one year after IT was compared. Twenty-two children completed the treatment course, and 13 age-matched healthy children served as controls. Adherent monocytes were isolated and stimulated with either crude mite extract of Dermatophagoid farinae (Df) for 7 days or lipopolysaccharide (LPS) for 3 days. The amount of TNF and IL-1 in culture supernatant was quantified by TNF and IL-1 enzyme-linked immunosorbent assay (ELISA) kits, respectively. The LPS-stimulated TNF production in patients was not different before or after IT (245.8 +/- 110.9 vs. 213.3 +/- 161.6 pg/0.1 ml, p +/- 0.202), but was significantly higher than the control (66.7 +/- 42.7 pg/0.1 ml; p less than 0.0001). The LPS-stimulated IL-1 production was similar among the three groups. When stimulated with Df antigen, monocytes from asthmatic patients produced a greater amount of TNF and IL-1 than did those from the control (p less than 0.001). Furthermore, although the production of TNF decreased after successful IT (360.2 +/- 181.6 vs 243.9 +/- 189.1 pg/0.1 ml, p less than 0.05), the production of IL-1 did not change (679.9 +/- 254.1 vs. 534.8 +/- 257.6 pg/0.1 ml, p greater than 0.05). Thus, repeated long-term administration of allergen (IT) was able to suppress specifically the TNF, but not IL-1 production of monocytes.(ABSTRACT TRUNCATED AT 250 WORDS)