Effects of cedar pollen extract on the immune system in vitro

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Prevention of allergic rhinitis by aldose reductase inhibition in a murine model.

BACKGROUND: Allergic rhinitis, one of the most common atopic diseases, is known to be elicited by Th2 cytokine-mediated inflammatory response. We have shown earlier that a polyol pathway enzyme aldose reductase (AR) regulates airway inflammation; however its role in allergic rhinitis is not known. We have investigated the role of AR in mediating pathological symptoms associated with allergic rhinitis in mice. METHODS: The wild-type (WT) mice treated without or with AR inhibitor and AR knock out (AR(-/-)) mice were sensitized by two intraperitoneal injections of ragweed pollen extract (RWE) with adjuvant alum on days 0 and 4 followed by challenge on day 11 and/or 18 and 25. The allergic rhinitis symptoms were assessed by monitoring the nasal scratch, mast cell degranulation and release of tryptase in nasal lavage, infiltration of inflammatory cells, production of inflammatory cytokines and nasal epithelium remodeling. RESULTS: Sensitization and challenge of mice with RWE produced robust and reproducible pathological symptoms of allergic rhinitis as compared to control mice. AR inhibitor, fidarestat administered mice showed markedly reduced early phase response to allergen exposure such as nasal scratches, mast cells degranulation and release of tryptase in the nasal passage as well as late phase response such as inflammatory cell infiltration and release of Th2 type cytokines and nasal epithelial remodeling. Further, prevention of these events in AR(-/-)) mice suggests the role of AR in the mediation of allergic rhinitis. CONCLUSION: These results indicate an important role of AR in the mediation of RWE-induced allergic rhinitis in mice and prevention by AR inhibitor, fidarestat offers a novel therapeutic approach to ameliorate allergic rhinitis.

Association of the MMP9 gene with childhood cedar pollen sensitization and pollinosis.

Matrix metalloproteinase 9 (MMP9) gene has been shown to be involved in the pathogenesis of allergic rhinitis (AR) and asthma. Previous studies suggested that single-nucleotide polymorphisms (SNPs) of the MMP9 gene conferred a risk for childhood asthma. However, whether the SNPs confer a risk for AR has not been previously investigated. The objective of this study was to investigate whether SNPs of the MMP9 gene are associated with risk of seasonal AR (pollinosis), perennial AR and allergen sensitization. A total of 670 school children were recruited in Japan and genotyped for functional polymorphism in the promoter (-1590C/T: rs3918242) and three amino-acid substitutions (R297Q: rs17576; P574R: rs2250889; R668Q: rs17577). Serum levels of total and specific IgE were determined. Disease status and other clinical characteristics of the subjects were investigated using a questionnaire. Associations between the MMP9 SNPs and both AR and serum IgE levels were evaluated. -1590C/T showed significant association with cedar pollinosis (corrected P (Pcor)=0.039). R668Q was in strong linkage disequilibrium (LD) with -1590C/T and showed significant association with cedar pollinosis (Pcor=0.023) and serum cedar pollen-specific IgE level (Pcor=0.022). A haplotype associated with -1590T and 668Q showed a significant association with cedar pollinosis, orchard grass pollinosis and cedar pollen-specific IgE (Pcor=0.0012, Pcor=0.0059 and Pcor=0.0041, respectively). R297Q and P574R were in weak LD with the rest of the SNPs and did not show significant association with disease. Compared with wild-type MMP9 protein (279R-574P-668R), a variant enzyme (279R-574P-668Q) that showed association with pollinosis had lower activity. However, lower enzyme activity was not associated with disease risk because another variant (279Q-574R-668R) showed lower enzyme activity but was not associated with pollinosis. The -1590T allele and its corresponding haplotype was associated with higher promoter activity and with pollen-specific IgE levels and pollinosis, suggesting that -1590C/T may have more impact on sensitization and disease development than R668Q. Our results suggest that the MMP9 gene confers susceptibility to cedar pollinosis in Japanese children. The MMP9 gene may be associated with pollinosis through sensitization processes.

Aldose reductase deficiency in mice protects from ragweed pollen extract (RWE)-induced allergic asthma.

BACKGROUND: Childhood hospitalization related to asthma remains at historically high levels, and its incidence is on the rise world-wide. Previously, we have demonstrated that aldose reductase (AR), a regulatory enzyme of polyol pathway, is a major mediator of allergen-induced asthma pathogenesis in mouse models. Here, using AR null (AR-/-) mice we have investigated the effect of AR deficiency on the pathogenesis of ragweed pollen extract (RWE)-induced allergic asthma in mice and also examined the efficacy of enteral administration of highly specific AR inhibitor, fidarestat. METHODS: The wild type (WT) and AR-/- mice were sensitized and challenged with RWE to induce allergic asthma. AR inhibitor, fidarestat was administered orally. Airway hyper-responsiveness was measured in unrestrained animals using whole body plethysmography. Mucin levels and Th2 cytokine in broncho-alveolar lavage (BAL) were determined using mouse anti-Muc5A/C ELISA kit and multiplex cytokine array, respectively. Eosinophils infiltration and goblet cells were assessed by H&E and periodic acid Schiff (PAS)-staining of formalin-fixed, paraffin-embedded lung sections. T regulatory cells were assessed in spleen derived CD4+CD25+ T cells population. RESULTS: Deficiency of AR in mice led to significantly decreased PENH, a marker of airway hyper-responsiveness, metaplasia of airway epithelial cells and mucus hyper-secretion following RWE-challenge. This was accompanied by a dramatic decrease in infiltration of eosinophils into sub-epithelium of lung as well as in BAL and release of Th2 cytokines in response to RWE-challenge of AR-/- mice. Further, enteral administration of fidarestat significantly prevented eosinophils infiltration, airway hyper-responsiveness and also markedly increased population of T regulatory (CD4+CD25+FoxP3+) cells as compared to RWE-sensitized and challenged mice not treated with fidarestat. CONCLUSION: Our results using AR-/- mice strongly suggest the role of AR in allergic asthma pathogenesis and effectiveness of oral administration of AR inhibitor in RWE-induced asthma in mice supports the use of AR inhibitors in the treatment of allergic asthma.

Simultaneous flow cytometric detection of basophil activation marker CD63 and intracellular phosphorylated p38 mitogen-activated protein kinase in birch pollen allergy.

BACKGROUND: Phosphorylation of p38 MAPK is a crucial step in IgE-receptor signaling in basophils. The relation of p38 MAPK to the well-validated diagnostic cell surface marker CD63 has not been evaluated in a clinical allergy model. METHODS: Expression of CD63 and phosphorylation of p38 MAPK were analyzed flow cytometrically in anti-IgE-gated basophils from 18 birch pollen allergic patients, five grass pollen allergic patients, and five healthy individuals, after 3 and 20 min of stimulation with recombinant major birch pollen allergen (rBet v 1). Additional time points and the influence of p38 MAPK inhibitor SB203580 were studied in birch pollen allergic patients. RESULTS: Phospho-p38 MAPK and CD63 were expressed dose-dependently in birch pollen allergic patient basophils within 1 minute of rBet v 1 stimulation. P38 MAPK phosphorylation was fastest and subsided gradually while CD63 expression remained elevated for at least 20 min. Inhibition of p38 MAPK significantly inhibited CD63 upregulation. With optimal stimulation of the cells (1 µg/mL), sensitivity and specificity for the discrimination between patients and a group of control individuals (grass pollen allergic patients and healthy controls) were 94% and 100% for CD63 at 3 and 20 min and for phospho-p38 MAPK at 3 min. CONCLUSION: Antigen-induced p38 MAPK phosphorylation in human basophils essentially contributes to CD63 upregulation. It is a sensitive and specific intracellular marker for allergy diagnosis and offers new insight into the mechanisms of basophil activation.

Monitoring antioxidant enzymes in red cells during allergen immunotherapy.

The aim of this report was to answer the question how specific immunotherapy influences the antioxidant enzyme system in patients with respiratory allergy and in longer perspective to find markers suitable to assess the efficacy of treatment. In open prospective randomised study 28 patients (18 females and 10 males, age 14-48 years) with seasonal respiratory allergy were treated with allergen immunotherapy. Subjects received subcutaneous therapy with allergens absorbed on calcium phoshate or aluminium hydroxide and were analyzed by the established protocol at the beginning, after three and 12 month of the treatment. In all treatment group red cell superoxide dismutase and glutathione peroxidase activities were in the normal range in allergic patients both before and during the treatment. Catalase activity in the allergic patients was lower as compared with controls and a significant increase of the enzyme activity occurred during and at the end of the treatment. In patients treated with calcium phosphate adsorbed allergen there was a continous increase of catalase activity from beginning up to the end of observation. In the case of the aluminium hydroxide treatment there was an increase from the baseline values up in the third month of the treatment and a decrease on the 12th month. In summary, the present results open the question that allergen immunotherapy may cause imbalance of oxidants and antioxidants. To support our findings larger controlled field studies are needed.

The urokinase system in patients with intermittent and persistent allergic rhinitis.

Local and systemic changes in hemostasis are associated with allergic diseases. Apart from their well documented role in regulation of plasminogen activation, components of the urokinase system may be involved in modulation of cellular activities during immune inflammatory responses. So far, little has been known about the function of the system in allergic inflammation. In the present study, we assessed circulating levels of the urokinase system components such as urokinase-type plasminogen activator (uPA), soluble form of uPA receptor (CD87), and the inhibitor--plasminogen activator inhibitor type 1. The study comprised of patients suffering from allergic rhinitis, however, without any asthmatic symptoms. Plasma levels of uPA and soluble form of uPA receptor antigens, and plasminogen activator inhibitor type 1 activity were measured in 17 patients with grass pollens-induced intermittent allergic rhinitis and 15 patients with persistent allergic rhinitis due to house dust mite allergy, as well as in 20 sex-matched and age-matched healthy nonatopic participants. We did not observe any statistically significant differences in the levels of the urokinase system components between patients with intermittent allergic rhinitis and persistent allergic rhinitis, and the controls. The circulating levels of uPA, its soluble receptor, and its inhibitor did not differ between allergic rhinitis patients and healthy participants, therefore it seems that the systemic release and activity of the urokinase system molecules may be not significantly changed in the course of nasal allergic inflammation induced by periodic or continuous exposure to a natural allergen.

Monitoring antioxidant enzymes in red cells during allergen immunotherapy

The aim of this report was to answer the question how specific immunotherapyinfluences the antioxidant enzyme system in patients with respiratory allergy and inlonger perspective to find markers suitable to assess the efficacy of treatment. In openprospective randomised study 28 patients (18 females and 10 males, age 14 – 48 years)with seasonal respiratory allergy were treated with allergen immunotherapy. Subjectsreceived subcutaneous therapy with allergens absorbed on calcium phoshate or aluminiumhydroxide and were analyzed by the established protocol at the beginning,after three and 12 month of the treatment. In all treatment group red cell superoxidedismutase and glutathione peroxidase activities were in the normal range in allergicpatients both before and during the treatment. Catalase activity in the allergicpatients was lower as compared with controls and a significant increase of theenzyme activity occurred during and at the end of the treatment. In patients treatedwith calcium phosphate adsorbed allergen there was a continous increase of catalaseactivity from beginning up to the end of observation. In the case of the aluminiumhydroxide treatment there was an increase from the baseline values up in the thirdmonth of the treatment and a decrease on the 12th month. In summary, the presentresults open the question that allergen immunotherapy may cause imbalance of oxidantsand antioxidants. To support our findings larger controlled field studies areneeded (AU)

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Nasal mucosal expression of nitric oxide synthases in patients with allergic rhinitis and its relation to asthma.

BACKGROUND: Nitric oxide (NO) has contradictory roles in the pathophysiology of allergic inflammation in both allergic rhinitis (AR) and asthma. Small amounts of NO produced by constitutive NO synthase (NOS) is anti-inflammatory, whereas large amounts produced by inducible NOS (iNOS) are proinflammatory. OBJECTIVE: To investigate the difference in constitutive endothelial NOS (eNOS) and iNOS expression in nonallergic and allergic mucosa and the possible relation of this to the coexistence of asthma in seasonal AR. METHODS: Seventeen patients (10 women and 7 men) with seasonal AR and 9 nonallergic patients (5 women and 4 men) with nasal septum deviation were enrolled. Inferior turbinate nasal biopsy specimens were obtained in all. Levels of eNOS and iNOS expressed as immunohistochemical scores (HSCOREs) were determined immunohistochemically from the specimens. RESULTS: The mean +/- SD HSCOREs for eNOS in patients with seasonal AR were not significantly different from those of the nonallergic controls (1.85 +/- 0.78 vs 1.63 +/- 0.54; P = .12). On the other hand, the mean +/- SD HSCOREs for iNOS were significantly higher in patients with seasonal AR (1.75 +/- 0.75 vs 0.71 +/- 0.6; P = .004). Furthermore, although eNOS expression was not different between seasonal AR patients with and without asthma, the mean +/- SD HSCOREs for iNOS were significantly higher in the patients with asthma (1.93 +/- 0.78 vs 1.65 +/- 0.55; P = .01). CONCLUSION: Increased expression of iNOS might have a role in the development of allergic inflammation in upper and lower airways and in comorbidity of AR and asthma.

Protease activity of allergenic pollen of cedar, cypress, juniper, birch and ragweed.

BACKGROUND: Pollen is an important trigger of allergic rhinitis, conjunctivitis, and/or asthma, and an exacerbating factor in atopic dermatitis. Although it is proposed that protease activity from allergen sources, such as mites, enhances allergenicity, little information is available on that from relevant allergenic pollens such as Japanese cedar and Japanese cypress pollens, which are the major cause of pollinosis in Japan. METHODS: We analyzed the protease activities derived from allergenic pollen of Japanese cedar, Japanese cypress, and Rocky mountain juniper, which belong to the Cupressaceae/Taxodiaceae family, and white birch and short ragweed, using synthetic substrates and class-specific inhibitors. RESULTS: We found that the pollen of the three members of the Cupressaceae/Taxodiaceae family contained serine protease activity, that the pollen of white birch and short ragweed contained not only serine protease activity but also cysteine protease activity, that all five types of pollen tested contained at least one other type of serine protease, whose sensitivity to a serine protease-specific inhibitor was relatively low, and that the content and releasability of the pollen-derived proteases differed according to the plant families. CONCLUSIONS: Clinically relevant allergenic pollens tested in the present study can release serine and/or cysteine endopeptidases. Information on the spectrum of the endopeptidase activities from these allergenic pollen grains will be useful for investigating their contribution to the pathogenesis of allergies.

Increased expression of lipoxygenase enzymes during pollen season in nasal biopsies of pollen-allergic patients.

BACKGROUND: Exposure of patients sensitized to pollen triggers development of seasonal allergic rhinitis symptoms (SAR). Eicosanoids are a group of arachidonic acid metabolites contributing to the symptoms of SAR. The aim of this study was to investigate seasonal changes in the expression of enzymes of the eicosanoid pathway in the nasal mucosa of patients with SAR. METHODS: Twenty SAR patients allergic to birch or grass and eight healthy subjects were included in the study. Patients registered rhinoconjunctivitis symptoms and use of rescue medication before and during the pollen season. Nasal biopsies were obtained before and around the peak of the season, sectioned and stained using markers for eosinophils, mast cells, T cells and neutrophils. Antibodies against the following enzymes were also used: cyclo-oxygenase (COX-1, COX-2), 5-lipoxygenase (5-LO), 5-lipoxygenase-activating factor (FLAP), LTA4 hydrolase (LTA4h) and LTC4 synthase (LTC4s). RESULTS: During the pollen season symptoms of rhinoconjunctivitis and medication score increased significantly (P=0.001; P=0.001 respectively). During the pollen season numbers of eosinophils (P=0.02) and cell positive 5-LO (P=0.02), LTC4s (P=0.04) and LTA4h (P=0.02) increased significantly. During season number of mast cells and cells expressing 5-LO and LTA4h were higher in SAR than in healthy controls group (P=0.02; P=0.01; P=0.03 respectively). CONCLUSION: In sensitized patients exposure to pollen allergen results in increased expression of enzymes of the eicosanoid pathway.

Spring brings breezes, wheezes, and pollen oxidases.

While the release of pollen into the air is essential for the reproduction of plants, the accidental yet inevitable uptake of pollen into human airways can cause symptoms of seasonal allergies and asthma. The symptomatic response to pollen is caused by granulocytes that produce inflammation, which is due in part to oxidative stress through the action of NADPH oxidases. The recruitment of these inflammatory granulocytes was previously thought to depend entirely on the activation of an adaptive immune response. In this issue of the JCI, Boldogh et al. demonstrate that pollens contain endogenous NADPH oxidase activity, which functions to generate local "danger signals" in nearby airway epithelium. These signals in turn trigger the early recruitment of granulocytes, even in the absence of the adaptive immune response. These findings suggest that inhibition of the pollen oxidase may provide a way to antagonize allergic inflammation at a very early step.

Allergen drives class switching to IgE in the nasal mucosa in allergic rhinitis.

IgE-expressing B cells are over 1000 times more frequent in the nasal B cell than the peripheral blood B cell population. We have investigated the provenance of these B cells in the nasal mucosa in allergic rhinitis. It is generally accepted that expression of activation-induced cytidine deaminase and class switch recombination (CSR) occur in lymphoid tissue, implying that IgE-committed B cells must migrate through the circulation to the nasal mucosa. Our detection of mRNA for activation-induced cytidine, multiple germline gene transcripts, and epsilon circle transcripts in the nasal mucosa of allergic, in contrast to nonallergic control subjects, however, indicates that local CSR occurs in allergic rhinitis. The germline gene transcripts and epsilon circle transcripts in grass pollen-allergic subjects are up-regulated during the season and also when biopsies from allergic subjects are incubated with the allergen ex vivo. These results demonstrate that allergen stimulates local CSR to IgE, revealing a potential target for topical therapies in allergic rhinitis.

Asymptomatic atopy is associated with increased indoleamine 2,3-dioxygenase activity and interleukin-10 production during seasonal allergen exposure.

BACKGROUND: Indoleamine 2,3-dioxygenase (IDO) is a tryptophan (TRP)-catabolizing enzyme with regulatory effects on T cells. T cell inhibition is achieved through both TRP depletion and TRP metabolite accumulation in specific local tissue microenvironments. The expression of IDO activity by different types of antigen-presenting cells (APCs) has been shown to play a role in many instances of immunoregulation and tolerance induction. Induction of IDO after the engagement of the high-affinity receptor for IgE, FcepsilonRI, on atopic monocytes has been suggested to regulate T cell responses in atopic disorders. Interleukin-10 (IL-10), a cytokine known for its down-regulatory functions in the immune system, has recently been associated with the stable expression of IDO in mature tolerogenic dendritic cells. OBJECTIVE: This study was devised to understand the role of systemic IDO and IL-10 in the prevention of clinical apparent allergy. METHODS: The concentration of TRP and the break-down product kynurenine were measured by high-performance liquid chromatography in- and off-season in sera from patients with seasonal allergic rhinitis (n=12) and from clinically asymptomatic atopic patients sensitized to specific aeroallergens (n=12). Non-atopic (NA) individuals (n=12) served as control. The concentration of plasma IL-10 was determined in parallel from these donors by ELISA in- and off-season. RESULTS: In clinically unresponsive but aeroallergen-sensitized atopic individuals significantly higher systemic activity of IDO and increased plasma IL-10 levels were found during allergen exposure but not off-season compared to symptomatic atopic individuals with allergic rhinitis and NA individuals. CONCLUSION: Enhanced systemic IDO activity as well as increased systemic levels of IL-10 may contribute to the containment of allergic T cell responses and could be involved in the maintenance of a state of clinical unresponsiveness.

Neuronal nitric oxide synthase immunoreactivity in the nasal mucosa of patients with idiopathic and allergic rhinitis.

The localization of neuronal nitric oxide synthase (nNOS) in the mucosa of the inferior and middle turbinates of 30 patients with and without allergic rhinitis was examined by immunohistochemical methods. Staining of paraffin sections from allergic and nonallergic patients revealed nNOS immunoreactivity (nNOS-IR) in the muscular layer of vessels, in the basal portion of submucosal glands and in the periost and the osteocytes of the turbinate bones. In contrast to earlier investigations, nNOS-IR was also seen in the nasal respiratory epithelium of allergic and nonallergic patients. The immunostaining of sections of submucosal glands from allergic patients was stronger than that of sections from patients with idiopathic rhinitis or patients with no nasal obstruction. The present result - nNOS-IR around glands is elevated in patients with allergic rhinitis - could indicate that this enzyme is involved in the pathogenesis and symptomatology of allergic rhinitis.

[Myeloperoxidase (MPO) as a marker of neutrophil influx into nasal mucosa after recombinant IL-8 challenge]. / Mieloperoksydaza (MPO) jako marker naplywu neutrofilów do blony sluzowej nosa po prowokacji rekombinowana Il-8.

Myeloperoxidase (MPO) has been proposed to mirror the degree of neutrophil activation, however its role as a marker of the participation of neutrophils in allergic inflammation is still unclear as the literature is controversial. The aim of this study was to evaluate the MPO levels and neutrophil influx in nasal lavage after recombinant Il-8 challenge. Eight patients suffering from seasonal allergic rhinitis, hypersensitive to grass pollens, with average age 30.1 +/- 2.67 were challenged both with Il-8 and diluent for Il-8 on a subsequent day, in two phases: before the pollen season (unprimed mucosa) and during the season (primed mucosa). Nasal lavage with saline were collected before, during Il-8 or placebo challenge and 30 minutes, 2 hours and 3 hours after the challenge. The number of neutrophils and MPO levels in the nasal fluid were determined. After the challenge with Il-8 of primed mucosa the number of neutrophils increased from 28250 cells/ml at the baseline to 28778, 251020 and 333660 at 0, 5, 2 and 3 hours respectively. There was a statistically significant difference between cells number after diluent and Il-8 challenge (p < 0.05, Wilcoxon rank-sum test). The number of neutrophils in the nasal lavage of primed mucosa after Il-8 challenge was significantly higher (p < 0.005) at all time points in comparison with the diluent and Il-8 challenges in the unprimed mucosa. There was no difference (p < 0.05) in MPO levels in the nasal lavage between Il-8 (mean 17.43 ng/ml +/- 10.98) and diluent challenge (20.98 ng/ml +/- 11.89) of unprimed mucosa. In the primed mucosa fluid we observed a peak of MPO level at 2 hours time point, however that was not significant as compared to diluent challenge (p = 0.465). We did not find the relationship between MPO levels and the neutrophils number in the lavage (rank Spearman factor, rs = 0.258, p = 0.42). Due to the lack of statistically confirmed relationship between MPO level and the number of neutrophils, MPO seems to be of little value as a marker of neutrophil influx into nasal mucosa.

[Levels of interleukin-4, interleukin-5, tryptase and eosinophil cationic protein of nasal lavage fluid in pollen allergic rhinitis]. / Interleukin-4, interleukin-5, triptáz és eosinophil kationos proteinszintek meghatározása az orrmosó folyadékban rhinitis allergicában.

IL-4, IL-5, tryptase and eosinophil cationic protein levels were measured in nasal lavage fluid from 15 pollen allergic rhinitis beyond pollen season. Allergy was proved by prick test. There were 15 non allergic children in the control group. Specific nasal allergen provocation was performed on the rhinitic group. Nasal lavage were done before, 1 and 12 hours after the provocation. Before the nasal provocation the ECP and IL-4 levels were significantly higher in the allergic group compared to the non allergic group. The levels of tryptase, ECP and IL-4 rose significantly after the provocation. The results reflect to the possibility of an activated immune status in allergic rhinitis even without the presence of the triggering pollens. After the specific provocation elevated tryptase levels were measured, referring to the activity of the early phase of the I. type hypersensitivity reaction, while the ECP and IL-5 elevation to its late phase. According to our examinations it can be said, that tryptase, ECP and IL-5 might be used to detect the activation of the early and late phases of the IgE mediated hypersensitive reaction.

Inhibition of the sodium, potassium adenosine triphosphatase enzyme in peripheral blood mononuclear cells of subjects with allergic rhinitis.

BACKGROUND: Previous investigations have documented that a sodium, potassium adenosine triphosphatase (Na+,K+ ATPase) enzyme inhibitor is bound to the platelet membrane, displaced from the platelet membrane by freezing, and present in the plasma of subjects with allergic rhinitis. Others have shown that stimulation of Na+,K+ ATPase is an important early event in mitogen-induced activation of peripheral blood mononuclear cells. OBJECTIVE: The purpose of this study was to determine whether the Na+,K+ ATPase enzyme inhibition observed in the platelets of subjects with allergic rhinitis also extends to peripheral blood mononuclear cells. METHODS: Na+,K+ ATPase activity of a particulate fraction of sonicated peripheral blood mononuclear cells was determined by spectrophotometry in asymptomatic adults with and without allergic rhinitis. RESULTS: The mean Na+,K+ ATPase activity of peripheral blood mononuclear cells expressed as nanomoles per microgram protein per minute (nM/ microgram protein/ min) +/-1 standard deviation of the subjects with allergic rhinitis (n = 14) was 1.04 +/- 1.01, while that of the control subjects (n = 12) was 3.57 +/- 1.60 (P < or = .001). In contrast, when the peripheral blood mononuclear cell membranes were frozen and then thawed prior to assay, the mean Na+,K+ ATPase activity for the subjects with allergic rhinitis (n = 24) was 5.33 +/- 2.62, while that of the control subjects (n = 23) was 1.12 +/- 1.24 (P < or = .001). Samples from a subset of subjects (n = 5) were assayed for both pre-freezing and post-freezing Na+,K+ ATPase activity. The freezing process was associated with a striking increase in Na+,K+ ATPase levels of subjects with allergic rhinitis (4.42 +/- 2.06) but a decrease in those of the control subjects (-3.89 +/- 0.95; P < or = .001). CONCLUSIONS: These data demonstrate that peripheral blood mononuclear cells from subjects with allergic rhinitis, like platelets, possess a membrane-bound Na+,K+ ATPase inhibitor that is displaced from the membrane by freezing. In vivo Na+,K+ ATPase inhibition could have significant effects on the activation and function of peripheral blood mononuclear cells in subjects with allergic rhinitis.