I. Chanal

Comparison between RAST and Pharmacia CAP system: A new automated specific IgE assay

RAST represents the standard technique to titrate serum-specific IgE and was found to have a higher efficiency in the diagnosis of IgE-mediated allergy than other in vitro tests. Pharmacia CAP system (CAP) is a new solid-phase immunoassay, fully automated, used for the titration of specific IgE antibodies. Results are listed in kilounits per liter, equilibrated against the World Health Organization standard for IgE. RAST and CAP were compared in 106 unselected patients (6 to 59 years) characterized by a detailed clinical history and skin prick tests with standardized allergen extracts. IgE to cat, Dermatophagoides pteronyssinus, Alternaria, orchard grass, olive, and Parietaria pollen were tested; 470 tests were run. The specificity, sensitivity, and efficiency of both in vitro tests ranged from 85.5% to 100% except for olive pollen, in which the sensitivity of both in vitro tests was low (68.2% for the new test and 63.6% for RAST). Except for orchard-grass pollen, the sensitivity and specificity of CAP were better than that of RAST. There was a highly significant correlation between both tests (r range, between 0.864 to 0.987). CAP competes favorably with RAST and has the advantage of being automated and eliciting results in kilounits per liter.

Characteristics of intermittent and persistent allergic rhinitis: DREAMS study group

Background In the Allergic Rhinitis and its Impact on Asthma (ARIA) classification, intermittent and persistent rhinitis were proposed to replace seasonal and perennial allergic rhinitis (AR).

Differences in clinical and immunologic reactivity of patients allergic to grass pollens and to multiple-pollen species: II. Efficacy of a double-blind, placebo-controlled, specific immunotherapy with standardized extracts

The IgE response of patients only allergic to grass pollens differs from response of patients allergic to multiple-pollen species. The IgE immunoblots to orchard-grass pollens confirmed that polysensitized patients had more proteins revealed than patients only allergic to grass pollens. To determine if both groups of patients present a different response toward specific immunotherapy (IT), a double-blind, placebo-controlled study was performed in 70 patients. Patients receiving the active treatment had a rush IT with either a standardized orchard grass-pollen extract or with a standardized mixed-pollen extract prepared, depending on the sensitivity of the patients. The maintenance dose was defined as that dose effective in grass-pollen IT in previous experiments. The same equipotent maintenance dose was administered for all pollen species. Symptom-medication scores during the pollen season and nasal challenge with orchard grass-pollen grains demonstrated that grass pollen-allergic patients had a significantly improved efficacy by comparison to placebo treatment, whereas polysensitized patients had a nonsignificant improvement. Serum grass-pollen IgG was significantly increased after IT in both treated groups. This study demonstrate that the response toward specific IT differs in patients only allergic to grass pollens by comparison to polysensitized patients.

Correlation between symptoms and the threshold for release of mediators in nasal secretions during nasal challenge with grass-pollen grains

Nasal challenges with pollen grains represent one of the techniques of provocation. However, the clinical criteria of positivity are not clearly established. Nasal challenges with increasing numbers of orchard-grass pollen grains were performed in 60 patients allergic to grass pollens and 20 normal subjects. Before any challenge, the nose was washed three times with saline and then lactose, and 50, 150, 450, 1350, and 4050 orchard-grass pollen grains were insufflated into the nostrils until a symptom score of 5 was reached. This score was mainly based on major symptoms of allergic rhinitis, for example, rhinorrhea, nasal obstruction, sneezes, and to a lesser extent, on minor symptoms, such as pruritus, conjunctivitis, and pharyngitis. Nasal secretions were obtained after each challenge by lavage. Histamine was titrated by a radioimmunoassay with a monoclonal antibody against acylated histamine. Prostaglandin D2 (PGD2) was assayed with an enzyme immunoassay with a polyclonal antibody against PGD2 methoxamine. None of the normal subjects had a symptom score greater than 2; 55/60 patients had a positive challenge. The release of PGD2 was significantly (p less than 0.001, Kruskal-Wallis test) correlated with a symptom score of 5; 74.5% of patients had a significant release of PGD2 in nasal secretions. In contrast, although 58.2% of patients had a release of histamine in nasal secretions when the challenge was positive, the correlation with symptom scores was not significant. PGD2 in nasal secretions increased 3.7-fold after a positive nasal challenge.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence of nasal polyposis in France: a cross-sectional, case-control study

Background:  The prevalence of nasal polyposis (NP) has never been established in France due to the lack of diagnostic tools for population‐based studies.

Antiallergic activity of H1-receptor antagonists assessed by nasal challenge

Most oral drugs used for the treatment of allergic rhinitis are classified as H1-receptor antagonists, and although they represent major sales throughout the world, their mechanism of action is still poorly known. In an attempt to understand better the in vivo therapeutic effects of these drugs, a double-blind, crossover study was carried out. The study compared the effects of terfenadine and loratadine, nonsedative H1-receptor antagonists, on the immediate allergic response of the upper airways to challenge with orchard-grass pollens in 14 highly allergic subjects. Increasing numbers of pollen grains were insufflated into the nostrils, and the response of the subjects was assessed by examining symptoms and measuring the release of histamine and prostaglandin D2 in nasal secretions. Each drug was administered for a week before challenge. This study demonstrated the clinical efficacy of both drugs by comparison to that of a control day, since symptoms were observed for a significantly (p = 0.014) greater number of pollen grains. Only one patient had a significant release of histamine when they were treated with loratadine versus 10 during control day (p less than 0.0023) and six when they were treated with terfenadine (p less than 0.01). Prostaglandin D2 release occurred with a higher allergen dose when patients were treated with both drugs. This study indicates that some H1 antagonists also possess antiallergic activities.

Seasonal variations of interleukin-4 and interferon-γ release by peripheral blood mononuclear cells from atopic subjects stimulated by polyclonal activators ☆ ☆☆ ★ ★★

Abstract IgE synthesis is controlled by interleukin (IL)-4 and interferon (IFN)-γ, but there is heterogeneity in the IL-4 response depending on the sensitization of patients and natural allergen exposure. In patients sensitized to various allergens, we studied the synthesis of IL-4, IFN-γ, and IgE to determine to what extent their in vitro immune response may be influenced by pollen season, depending on their sensitization. We studied 12 nonallergic individuals, seven patients sensitized to cypress pollen, 12 sensitized to grass pollen, 14 sensitized to several pollens, and 42 patients with polysensitization. The release of IL-4 and IFN-γ from peripheral blood mononuclear cells stimulated by polyclonal agents (calcium ionophore A23187 and phorbol myristate acetate) was measured by ELISA. The spontaneous and IL-4-induced release of IgE was measured by ELISA. In patients with cypress pollen allergy, IL-4 and IgE release were significantly lower than in patients with other allergies. In the pollen-sensitized group, IL-4 and IgE release were significantly higher during the pollen season than out of it. No variation in IL-4 or IgE release was observed in the polysensitized group. IFN-γ production was not affected by the pollen season. These data show that the seasonal variations of IL-4 and IgE synthesis differ according to the sensitization of patients. (J ALLERGY CLIN IMMUNOL 1995;96:932-40.)

Precision of conjunctival provocation tests in right and left eyes

BACKGROUND Conjunctival provocation tests (CPTs) are used for assessing the efficacy of antiallergic treatments, but their reproducibility is not well characterized. A study was carried out to assess the reproducibility of CPTs and the release of mediators during CPTs. METHODS Both eyes of 30 grass-pollen-allergic patients were challenged with threefold increasing concentrations of a standardized orchard grass pollen extract. The positivity of the CPT was assessed by a cumulative symptom score. The release of mediators was examined by means of histamine (radioimmunoassay), prostaglandin D2 and leukotrienes C4 and D4 (enzyme immunoassay). RESULTS There was a significant correlation between the concentrations of allergen inducing a positive CPT in both eyes (p < 0.0001, Spearman). All but one patient had a significant release of at least one mediator. After allergen CPT there was a significant release in both eyes in 13 of 20 patients for prostaglandin D2, 11 of 19 for leukotrienes C4 and D4 and 15 of 18 for histamine. The correlations between the levels of mediators released during diluent and allergen challenges in both eyes were significant for prostaglandin D2 (diluent and allergen challenges) and leukotrienes C4 and D4 (allergen challenge). CONCLUSION Considering the whole group of patients, CPT is reproducible in both eyes, but the results are less satisfactory when patients are examined individually.

Lack of subsensitivity to loratadine during long-term dosing during 12 weeks**

The development of subsensitivity to first-generation H1 blockers often occurs within days or weeks of treatment. It is manifested by a decrease in efficacy and a waning of the inhibition of skin reactivity to allergen or histamine. Subsensitivity to loratadine was investigated in a double-blind, placebo-controlled parallel group study in 20 allergic subjects (22 to 35 years) who received either placebo or loratadine (10 mg one daily) for 12 weeks. Skin prick tests were done with six threefold increasing concentrations of standardized allergen extracts (orchard grass or mite) and histamine-coated Phazet. Skin tests were done before any treatment and after 7, 28, 56, and 84 days. Wheals and flares were measured. Compliance was monitored strictly during the study. Statistical analysis was done by parallel line bioassay and Wilcoxon W test. Skin test reactivity to histamine or allergen did not change throughout the trial in the placebo-treated group. Patients treated by loratadine had a significantly smaller wheal-and-flare reaction after 7 days. This effect was greater at 28 days and lasted throughout the treatment period. This study demonstrates that subsensitivity to loratadine measured by histamine and allergen skin tests does not develop during a 12-week period.

Reduction of soluble ICAM‐1 levels in nasal secretion by H1‐blockers in seasonal allergic rhinitis

ICAM‐1, a transmembrane glycoprotein promoting adhesion in immunologic and inflammatory reactions, was found to be increased on nasal epithelial cells of patients with allergic rhinitis. Loratadinae, an H1‐Mocker, was found to reduce in vitro the expression of ICAM‐1 on nasal epithelial cells. A double‐blind, parallel‐group study was carried out during the pollen season to compare the effect of two H1‐blockers, cetiraizine (10 mg OD) and loratadine (10 mg OD), on the release of soluble ICAM‐1 in nasal secretions. A group of untreated patients was used as a control group. sICAM‐1 was measured by enzyme immunoassay before and after 2 weeks of treatment. Symptoms were significantly decreased in the actively treated groups. sICAM‐1 levels were unchanged in the control group but were significantly reduced in the two treated groups (P<0.015, Wilcoxons W test). This study shows that two H1‐blockers, loratadine and cetirizinae, have a similar effect on sICAM‐1 released in nasal secretions during the pollen season.