Lymphocyte proliferative responses to the purified Dermatophagoides farinae major allergen in untreated and hyposensitized atopic patients.

We investigated the proliferative response of lymphocytes from mite-sensitive patients (RAST D.far greater than 3.5 PRU/ml) in the presence of the major allergen Der.f.I purified from Dermatophagoides farinae. Comparative studies were carried out with peripheral blood mononuclear cells from non-atopic donors (RAST = 0), and from patients undergoing hyposensitization treatment (5 to 24 months). According to Student's t-test, there was no significant difference in the Der.f.I-induced proliferation of peripheral blood mononuclear cells from normal donors, untreated atopic patients and hyposensitized patients. In conclusion, it was impossible to discriminate between normal donors, atopic patients and hyposensitized patients with regard to their circulating lymphocyte responses to the purified major allergen Der.f.I.

Eosinophil infiltration: effects of H1 antihistamines.

This article reviews the contribution of cell-mediated inflammatory responses to the immediate immunoglobulin E-dependent allergic reaction. Apparently eosinophils play an important part in the pathogenesis of allergic reactions. Some new H1 antihistamines may also have non-H1-mediated antiinflammatory properties. In two double-blind, placebo-controlled, crossover studies of allergic and normal subjects, we showed that oral cetirizine, at dosages of 10 and 20 mg/day, significantly inhibited wheal-and-erythema reactions induced by grass pollen, 48/80, histamine, platelet-activating factor acether, and N-formyl-methionyl-leucyl-phenylalanine. In the first study, cutaneous eosinophil migration was significantly inhibited by cetirizine at pollen and 48/80 skin test sites (61%, p less than 0.01, and 53%, p less than 0.01, respectively), although no change was observed at histamine skin test sites. Inhibition of neutrophil accumulation was also observed at pollen and 48/80 sites (41%, p less than 0.1, and 31%, p less than 0.1, respectively). Monocyte accumulation was not affected by cetirizine. In the second study, cetirizine suppressed the eosinophil influx induced by pollen, platelet-activating factor, 400 ng, and platelet-activating factor, 40 ng (63%, p less than 0.001; 58.5%, p less than 0.001; and 57.8%, p less than 0.01, respectively). This inhibition was effective 2 hours after challenge and persisted through hours 4, 8, and 24. N-Formyl-methionyl-leucyl-phenylalanine induced a weak eosinophil accumulation that was inhibited by cetirizine.

In vivo effects of cetirizine on cutaneous reactivity and eosinophil migration induced by platelet-activating factor (PAF-acether) in man.

The aim of the study was to determine the effect of cetirizine, a new potent H1 antihistamine, on acute cutaneous inflammatory response and eosinophil accumulation induced in vivo by platelet-activating-factor (PAF-acether) and allergen. In a double-blind, crossover study, seven subjects allergic to grass pollen and three nonallergic control subjects received orally either cetirizine, 20 mg/day, or placebo for 4 days. On day 4, the subjects were skin tested with grass pollen and PAF-acether (400 and 40 ng per site). After the challenge, an evaluation of time-course cutaneous eosinophil infiltrations by a skin window technique was performed. Cetirizine pretreatment reduced skin wheal and erythema elicited by allergen and PAF, 400 and 40 ng, by 74.6% (p less than 0.001), 53.9% (p less than 0.001), and 47% (p less than 0.01), respectively. Skin reactivity induced by PAF-acether was also significantly reduced by cetirizine in nonallergic subjects. Cetirizine reduced at hour 24 eosinophil infiltrations induced by allergen and PAF, 400 and 40 ng, by 63% (p less than 0.001), 58.5% (p less than 0.001), and 57.8% (p less than 0.01), respectively. This inhibitory effect of cetirizine on allergen and PAF-induced eosinophil infiltration was already effective 2 hours after the challenge. PAF induced a nonsignificant eosinophil influx in all nonallergic subjects. In conclusion, cetirizine inhibited both the immediate cutaneous response and the eosinophil influx induced by allergen and by a potent eosinophil chemotactic factor, such as PAF-acether. Therefore, cetirizine, besides its anti-H1 effect, has the potential to modulate the allergic inflammatory response.

Exercise-induced anaphylaxis: useful screening of food sensitization.

BACKGROUND AND OBJECTIVES: Exercise-induced anaphylaxis is a well-defined entity as described by Sheffer and Austen. Exercise-induced anaphylaxis can be associated with ingestion of a specific food. We report our experience with a series of cases of exercise-induced anaphylaxis in which anaphylaxis was considered to be associated with food allergy. METHODS: We observed 19 patients in whom severe systemic signs of anaphylaxis occurred during or immediately after exercise, while the severity of reactions excluded challenge testing. The causal relationship with various foods was systematically investigated in all cases, even in the absence of any history of allergy. RESULTS: Sensitization to wheat flour was demonstrated in 12 patients, to peanut in seven, and to tree nuts in six cases with skin tests and/or RAST. Sensitivity to various other foods was found less often. Further, avoidance of specific foods according to results of skin tests and RAST was systematically observed during the five hours prior to exercise and no symptom occurred, suggesting a role of specific food intake in the pathogenesis of exercise-induced anaphylaxis. With such elimination diets, most of these young patients were able to engage in regular vigorous exercises (more than twice a week in some cases) without any clinical manifestation with a median followup of 2 years. In two patients, however, recurrence of exercise-induced anaphylaxis was subsequently explained by concomitant ingestion of other foods such as rice and peanut. Additional avoidance of these foods before exercise was then effective in 14 cases (median follow up: 2 years). CONCLUSIONS: Investigations to detect food sensitization, in particular to wheat, peanut and/or tree nuts, and specific avoidance of these foods five hours before exercise appear essential in cases of exercise-induced anaphylaxis.