Analysis of human nasal mucous glycoproteins

Relationship between free and total malondialdehyde, a well-established marker of oxidative stress, in various types of human biospecimens

BACKGROUND

Oxidative stress is involved in thoracic diseases and health responses to air pollution. Malondialdehyde (MDA) is a well-established marker of oxidative stress, but it may be present in unconjugated and conjugated forms. To our knowledge, no studies have conducted a systemic evaluation of both free MDA (unconjugated MDA) and total MDA (the sum of both unconjugated and conjugated MDA) across various types of human biospecimens.

METHODS

Free MDA and total MDA were simultaneously measured in a range of human biospecimens, including nasal fluid (N=158), saliva (N=158), exhaled breath condensate (N=40), serum (N=232), and urine (N=429). All samples were analyzed using an HPLC-fluorescence method with high sensitivity and specificity. Due to the right skewed distribution of free MDA and total MDA, we performed natural-log transformation before subsequent statistical analyses. The relationship between the natural log of free and total MDA was evaluated by R2 of simple linear regression. T test was used for comparisons of means between two groups. One-way analysis of variance was used in combination with Tukey's test to compare the natural log of the ratio of free MDA to total MDA across various types of biospecimens.

RESULTS

For exhaled breath condensate, serum, urine, nasal fluid and saliva samples, the R2 between free and total MDA were 0.61, 0.22, 0.59, 0.47 and 0.06, respectively; the medians of the free MDA to total MDA ratio were 48.1%, 17.4%, 9.8%, 5.1% and 3.0%, respectively; the free MDA to total MDA ratio in EBC > serum > urine > nasal fluid > saliva (P<0.001 for pairwise comparisons).

CONCLUSIONS

For exhaled breath condensate and urine samples, using either free or total MDA can provide information regarding the level of oxidative stress; however, that is not the case for serum, nasal fluid, and saliva given the low correlations between free and total MDA.

Localization of m3 Muscarinic Receptor mRNA in Human Nasal Mucosa

Cholinergic nerves play an important part in the regulation of nasal secretions and nasal patency. In situ hybridization was used to identify the cells in human nasal mucosa that express the muscarinic m3 receptor mRNA, which codes for the M3 muscarinic receptor subtype protein. An m3 cDNA probe was biotin-labeled using terminal transferase and hybridized to tissue sections of formaldehyde- or formaldehyde/microwave irradiation-fixed human nasal mucosa. The biotinylated probe was detected using gold-labeled antibiotin antibodies with silver enhancement. Muscarinic m3 receptor mRNA was identified in all epithelial cells, both serous and mucous cells of submucosal glands, and endothelial cells of small muscular arteries, veins, and capillaries. This suggests that M3 receptors may mediate glandular secretion and vasomotor effects. M3-receptor antagonists active at these sites may reduce the glandular secretion and vasodilation that is produced by parasympathetic reflex activity in allergic and nonallergic rhinitis.

Hyperviscoelasticity of epipharyngeal mucus may induce globus pharyngis

Detailed observation reveals a lump of translucent sticky mucus standing in the epipharynx of most globus patients, suggesting that the mucus adherent to the epipharynx causes a globus sensation. The epipharyngeal mucus of 70 consecutive globus patients was sampled via the nasal cavity. Fucose and sialic acid, the determinants of the viscoelasticity of mucus, were measured. Twenty-three patients were also asked to complete the Throat Questionnaire so we could evaluate the correlation between the degree of globus sensation and the viscoelasticity of the mucus. The mucus of 10 healthy subjects was sampled, analyzed, and compared with the data of the patients. The fucose and sialic acid concentrations found in the patients with globus pharyngis were significantly higher than those in the control subjects (Mann-Whitney U test, p < .01). The fucose concentrations correlated significantly with the globus pharyngis scores (Spearman correlation, p < .05). We conclude that there is a close association between stagnant mucus in the epipharynx and globus sensation.

The in-vitro activity of povidone-iodinecream against Staphylococcus aureus and its bioavailability in nasal secretions

Due to the emergence of mupirocin-resistance in some epidemic strains of methicillin resistant Staphylococcus aureus (EMRSA) and the appearance of EMRSA with intermediate resistance to vancomycin, we evaluated the in-vitro activity of 5% povidone-iodine ('Betadine') cream as a possiblealternative to mupirocin for the elimination of nasal carriage of S. aureus. As judged by enrichment culture, povidone-iodine was bactericidal against three mupirocin-sensitive strains of S. aureus from nasal carriers, and against mupirocin-resistant and -sensitive strains of EMRSA types 3, 15 and 16, after incubation with povidone-iodine for 1.0 min at 32 degrees C. Mupirocin nasal ointment did not prevent growth after 180 min incubation. In a quantitative suspension test, 1:100 dilution of povidone-iodine cream completely eliminated an inoculum of 10(8)cfu/mL of all nine test organisms after incubation at 32 degrees C for 1.0 min, and 1:1000 dilution reduced cfu, by a factor of 10(5). After direct inoculation of the povidone-iodine cream to give 10(5)cfu/g, none of the test strains were recoverable after 30 s, giving a killing rate of approximately 10(4)cfu/s; for mupirocin nasal ointment, the maximum reduction of mupirocin-sensitive strains was ten fold after 3 h. Povidone-iodine activity was not detectable in sensitivity-testing agar, although 0.025% of povidone-iodine was detectable in a 15% nutrient strength tryptone soya agar. Using this minimal medium, the addition of nasal secretions (from any of 11 samples) reduced the activity of povidone-iodine by 80-90%, but mupirocin activity was unaffected. One millilitre of nasal secretions inactivated the equivalent of approximately 22.5 mg of povidone-iodine. These results suggest that povidone-iodine cream may have a role in the prevention of colonization and infection caused by MRSA, including mupirocin-resistant strains.

In vitro antiviral activity of AG7088, a potent inhibitor of human rhinovirus 3C protease

AG7088 is a potent, irreversible inhibitor of human rhinovirus (HRV) 3C protease (inactivation rate constant (k(obs)/[I]) = 1,470,000 +/- 440,000 M(-1) s(-1) for HRV 14) that was discovered by protein structure-based drug design methodologies. In H1-HeLa and MRC-5 cell protection assays, AG7088 inhibited the replication of all HRV serotypes (48 of 48) tested with a mean 50% effective concentration (EC(50)) of 0.023 microM (range, 0.003 to 0.081 microM) and a mean EC(90) of 0.082 microM (range, 0.018 to 0.261 microM) as well as that of related picornaviruses including coxsackieviruses A21 and B3, enterovirus 70, and echovirus 11. No significant reductions in the antiviral activity of AG7088 were observed when assays were performed in the presence of alpha(1)-acid glycoprotein or mucin, proteins present in nasal secretions. The 50% cytotoxic concentration of AG7088 was >1,000 microM, yielding a therapeutic index of >12,346 to >333,333. In a single-cycle, time-of-addition assay, AG7088 demonstrated antiviral activity when added up to 6 h after infection. In contrast, a compound targeting viral attachment and/or uncoating was effective only when added at the initiation of virus infection. Direct inhibition of 3C proteolytic activity in infected cells treated with AG7088 was demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of radiolabeled proteins, which showed a dose-dependent accumulation of viral precursor polyproteins and reduction of processed protein products. The broad spectrum of antiviral activity of AG7088, combined with its efficacy even when added late in the virus life cycle, highlights the advantages of 3C protease as a target and suggests that AG7088 will be a promising clinical candidate.

Mucoglycoprotein hypersecretion in allergic rhinitis and cystic fibrosis

There is little information about specific changes in submucosal gland exocytosis in diseases such as allergic rhinitis (AR), nonallergic rhinitis (NAR), and cystic fibrosis (CF). Nasal lavage fluids were collected from normal, AR, NAR, and CF subjects. Concentrations of lysozyme, Alcian blue-staining mucoglycoconjugate material (AB + m), and human high-molecular-weight mucoglycoconjugates recognized by the 7F10 murine monoclonal antibody [7F10-immunoreactive mucoglycoconjugates (7F10-irm)] were measured. AB + m and 7F10-irm were characterized by Sepharose-2B column chromatography and glycosidase digestion. 7F10-irm was increased in CF (2.4-fold; P = 0.001) and AR (12.7-fold; P = 0.00007) subjects. AB + m was increased in CF (1.8-fold; P = 0.049) and AR (1.2-fold; P = 0.07) subjects. There were no changes in NAR subjects. On Sepharose-2B columns, AB + m peaks were at 1.3-3.0 x 10(6) and 0.36-0.65 x 10(6) Da. 7F10-irm showed four distinct peaks at 1.5, 1.2, 0.85, and 0.53 x 10(6) Da that were nearly identical in both normal and CF samples. Sialic acid was present in both 7F10-irm and AB + m. 7F10-irm and AB + m are mutually exclusive sialylated mucoglycoproteins that are significantly induced in AR and CF but not in NAR.

Contribution of endotracheal tubes to the pathogenesis of ventilator-associated pneumonia

The contribution of ventilatory equipment to the pathogenesis of ventilator-associated pneumonia (VAP) is well-established but the design of endotracheal tubes has been improved only to reduce tracheal traumatization. However many factors, including the surface properties of the endotracheal tube, humidity of the ventilatory gases, ventilatory mode and nursing management result in the formation of an infective, highly viscous and adhesive layer inside of the endotracheal tube. Endotracheal tubes may contribute to the pathogenesis of VAP when infective particles of this adhesive layer are dislodged into the lower airways by shear forces imparted by the respiratory gasflow. The current state of research is reviewed and potential solutions to this problem are discussed.

Endothelin in human nasal mucosa

Endothelin (ET), a potent vasoconstrictor and bronchoconstrictor peptide synthesized by endothelial and epithelial cells, was examined for its potential functions in human inferior turbinate nasal mucosal tissue by four techniques: (1) immunoreactive ET was localized in the mucosa by immunohistochemistry; (2) receptors for ET were identified by autoradiography employing [125I]ET; (3) ET-1 mRNA was localized by in situ hybridization; and (4) the secretory functions of ET were examined by the release of mucous and serous cell products after the addition of ET to human nasal turbinates in short-term cultures. Specific ET-1-immunoreactive material was found most extensively in small muscular arteries and in serous cells in submucosal glands. ET-1 was also found to a lower extent in the walls of venous sinusoids. [125I]ET-1 binding sites were localized by autoradiography to submucosal glands and to venous sinusoids and small muscular arterioles. mRNA for ET-1 was found most extensively in the venous sinusoids and to a lesser extent in small muscular arteries. In mucosal explant cultures, ET-1 and ET-2 stimulated lactoferrin and mucous glycoprotein release from serous and mucous cells, but ET-3 was inactive. The observations indicate that in the human nasal mucosa, ET is present in the vascular endothelium and the serous cells in submucosal glands and acts on glandular ET receptors to induce both serous and mucous cell secretion. It is also likely that ET plays a role in the regulation of vasomotor tone.

The effects of neuropeptides on mucous glycoprotein secretion from human nasal mucosa in vitro

The role of neuropeptides in the regulation of macromolecule secretion from human nasal mucosa is incompletely understood. Previous in vitro explant culture studies have demonstrated the effects of neuropeptides on lactoferrin release from serous cells and 3H-glucosamine labeled respiratory glycoconjugate secretion from mucus-containing cells. The generation of a new monoclonal antibody, 7F10, has led to the development of an ELISA for high molecular weight respiratory mucous glycoproteins (MGP). This ELISA was used to measure the ability of sensory, parasympathetic and sympathetic neuropeptides to stimulate MGP release from human nasal mucosal fragments in short term explant culture in vitro. Significant MGP release was stimulated by the sensory neuropeptides gastrin releasing peptide (10 microM GRP: 10.6% +/- 2.4% increase, n = 8, P less than 0.01 vs. control), substance P (1 microM SP: 12.5% +/- 5.4%, n = 11, P less than 0.05), neurokinin A (1 microM NKA: 17.8 +/- 4.3%, n = 6, P less than 0.01), while calcitonin gene related peptide (CGRP) was without effect. Vasoactive intestinal peptide (VIP), a neurotransmitter from parasympathetic nerves, induced significant dose dependent MGP secretion, but had no additive or inhibitory interaction with methacholine-induced secretion. Neuropeptide Y (NPY), present in sympathetic nerves, had no effect on MGP secretion. These observations correlate with the effects of neuropeptides on serous cell lactoferrin secretion, and the presence of specific GRP, SP, and VIP binding sites on human nasal submucosal glands that have been detected by autoradiography. GRP and tachykinins (SP and NKA) from sensory nerves, and VIP released during parasympathetic reflexes may significantly stimulate mucous and serous cell secretion from human nasal mucosa in vivo.

Endothelin-1 stimulates eicosanoid production in cultured human nasal mucosa

Endothelin (ET) has been shown to contract both vascular and nonvascular smooth muscle and to stimulate human nasal glandular secretion of serous and mucous cell products. Some effects of ET are thought to be mediated by eicosanoid production. To explore the direct effect of ET on arachidonate metabolism in cultured human nasal mucosal explants, eicosanoids were measured after ET-1 stimulation. After labeling the explants with [3H]arachidonic acid (AA), supernatant from control and ET-1-treated explants were fractionated by reverse-phase high-performance liquid chromatography (HPLC). The resulting elution pattern suggested the release of prostaglandin (PG) E2 and AA in response to ET-1 stimulation. Radioimmunoassay after HPLC resolution confirmed that ET-1 induced a significantly increased release of PGE2 as well as PGD2, PGF2 alpha, thromboxane B2, and 15-hydroxyeicosatetraenoic acid (15-HETE). Although significant amounts of 15-HETE were generated, cyclooxygenase product generation was most remarkable. Eicosanoid release after ET-1 exposure (10 to 0.1 microM) is concentration dependent and occurs within 1 h. Whereas 15-HETE release was maximal at 4 h, prostanoid production was maximal 1 h after exposure to ET-1. Other assayed AA metabolites, including the peptidoleukotrienes, did not significantly change after ET-1 stimulation. We conclude that ET-1 induces the release of predominantly cyclooxygenase products from cultured human nasal mucosal explants.

Immunohistochemical detection of serous cells in nasal mucosa with monoclonal antibody against a component in human nasal secretion

Secreting mechanisms of secretory cells in nasal mucosa and the changes of nasal secretions in chronic inflammatory sinusitis have been studied by the biochemical and histochemical methods. These methods could not clarify the changes of quality and quantity of nasal secretions and secretory cells. In order to obtain the specific marker for the secretions in different cells, we have produced monoclonal antibodies against a component in human nasal discharge. One antibody was selected for further characterization, because it stained submucosal serous cells specifically. This antibody stained the components of serous cells with molecular weight of 14 kD specifically, and was sensitive to periodate oxidation treatment. This antibody will be useful for detecting the subpopulation in secretory cells of human nasal mucosa, and may be serve as a biochemical probe for secretory activity of particular secretory cell types.

Human nasal respiratory secretions and host defense

The largest human body surface is the lining of the respiratory tract, gastrointestinal tract, and reproductive system each of which is covered by mucous membranes, named for their capacity to secrete mucus. Recent studies of mucus have defined some of the physiologic and pharmacologic controls of secretions. However, the constituents that are found in mucus and their roles in human health and disease are still in the initial phases of exploration. Human nasal respiratory secretions provide one convenient source of mucous membrane secretions. Nasal secretions include a variety of proteins, which appear to serve important functions in host-defense. Most, if not all, of the antiphlogistic products are synthesized and secreted by serous cells in the submucous glands, and it appears that the serous cell is the resident antimicrobial cell in mucous membranes.

Substance P and neurokinin A in human nasal mucosa

The tachykinins substance P (SP) and neurokinin A (NKA) were studied in human inferior turbinate nasal mucosa by radioimmunoassay, immunohistochemistry, and autoradiography and for their effect upon mucus release in an in vitro culture system in order to infer their potential functions in the upper respiratory tract. Similar amounts of SP (1.03 +/- 0.12 pmol/g wet weight; mean +/- SEM; n = 26) and NKA (0.76 +/- 0.23; n = 7) were found. NKA and SP immunoreactive nerve fibers were found in the walls of arterioles, venules, and sinusoids and as individual fibers in gland acini, near the basement membrane, and in the epithelium. [125I]SP bound to arterioles, venules, and glands. [125I]NKA bound only to arterioles. In short-term explant culture of fragments of human nasal mucosa, both 1 microM SP and 1 microM NKA stimulated release of [3H]glucosamine-labeled respiratory glycoconjugates. These results indicate that SP and NKA have similar distributions in nociceptive sensory nerves in human nasal mucosa. The distribution of [125I]SP binding sites is consistent with a role for SP as a vasodilator and mucous secretagogue. The presence of [125I] NKA binding sites on vessels suggests a primary role for NKA in regulating vasomotor tone.

Vasoactive intestinal peptide in human nasal mucosa

Vasoactive intestinal peptide (VIP), which is present with acetylcholine in parasympathetic nerve fibers, may have important regulatory functions in mucous membranes. The potential roles for VIP in human nasal mucosa were studied using an integrated approach. The VIP content of human nasal mucosa was determined to be 2.84 +/- 0.47 pmol/g wet weight (n = 8) by RIA. VIP-immunoreactive nerve fibers were found to be most concentrated in submucosal glands adjacent to serous and mucous cells. 125I-VIP binding sites were located on submucosal glands, epithelial cells, and arterioles. In short-term explant culture, VIP stimulated lactoferrin release from serous cells but did not stimulate [3H]glucosamine-labeled respiratory glycoconjugate secretion. Methacholine was more potent than VIP, and methacholine stimulated both lactoferrin and respiratory glycoconjugate release. The addition of VIP plus methacholine to explants resulted in additive increases in lactoferrin release. Based upon the autoradiographic distribution of 125I-VIP binding sites and the effects on explants, VIP derived from parasympathetic nerve fibers may function in the regulation of serous cell secretion in human nasal mucosa. VIP may also participate in the regulation of vasomotor tone.

Neuropeptide Y (NPY) in human nasal mucosa

Neuropeptide Y (NPY), a potent vasoconstrictor peptide found in sympathetic neurons, was analyzed in human inferior turbinate nasal mucosal tissue. NPY content determined by radioimmunoassay was 3.13 +/- 0.79 pmol/g tissue (n = 6) in mucosa extracted with ethanol-acetic acid. NPY-immunoreactive nerves were found around small muscular arteries, arterioles, arteriovenous anastomoses, and as free fibers near arteriolar and venous vessels. They formed a plexus around the arterial vessels, and were also present between vascular smooth muscle cells. Few NPY fibers were present near glands or the epithelium. [125I]NPY binding sites were localized by autoradiography to small muscular arteries, arterioles, and a few venous sinusoids. In explant culture experiments, 4 microM NPY did not stimulate release of [3H]glucosamine-labeled glycoconjugates or lactoferrin (a product of serous cells) from nasal mucosal fragments. Degradation of NPY by a tissue homogenate was rapid (t1/2 = 13.5 +/- 2.3 min). The degradation was inhibited by thiorphan and phosphoramidon, inhibitors of neutral endopeptidase activity. NPY released from sympathetic neurons may play a role as a constrictor of arterial vessels and regulate vasomotor tone in the human nasal mucosa.

Abnormal nasal glandular secretion in recurrent sinusitis

Recurrent sinusitis (RS) is a very common clinical problem for which no underlying cause can generally be ascertained. We examined nasal mucosal responses in 14 patients with RS to determine if a relative deficiency in secretion of glandular antimicrobial factors might play a role. Twenty-four subjects with no history of sinusitis were studied concurrently as normal control (NC) subjects. RS was defined by two or more episodes of acute sinusitis per year for 2 or more years. After provocation with 25 mg of methacholine or 1 mg of histamine, nasal washings were analyzed for total proteins: the plasma protein albumin, IgG, and nonsecretory IgA (nsIgA), and the glandular proteins secretory IgA (sIgA), lactoferrin (LFN), and lysozyme (LZM). Although baseline secretions in patients with RS were relatively enriched with LFN and LZM as compared to that of secretions in NC subjects, patients with RS had a blunted cholinergic response with decreased secretion of albumin, IgG, nsIgA, sIgA, and LZM. Histamine responses were equivalent in both patients with RS and NC subjects. After 4 to 12 months of medical treatment, the abnormal cholinergic responses improved on repeat methacholine challenge in all eight subjects with RS rechallenged. Thus, patients with RS have a reversible reduction in nasal mucosal secretory responses to cholinergic stimulation. Since glandular secretions are rich in antimicrobial factors, such as LFN, LZM, and sIgA, it appears possible that the inability to secrete glandular proteins normally may predispose to recurrent infections.

Bradykinin and respiratory mucous membranes. Analysis of bradykinin binding site distribution and secretory responses in vitro and in vivo

Bradykinin (BK) and lysyl-BK (lys-BK, kallidin) have been proposed as potentially important mediators of rhinorrhea. Possible mechanisms by which BK might contribute to rhinorrhea were investigated by several approaches. (1) The autoradiographic distribution of 125I-BK binding sites in human inferior turbinate nasal mucosa was determined. (2) The effects of BK and lys-BK and antagonists on radiolabeled respiratory glycoconjugate (RGC) release from human nasal mucosa was measured. (3) The secretory effects of BK were studied in cat tracheal mucosa maintained in short-term explant culture, and in ferret trachea maintained in Ussing chambers. (4) The effects of BK on macromolecule secretion in guinea pig nasal mucosa was studied in vivo. Autoradiographic examination of human nasal mucosa revealed that 125I-BK specifically bound to small muscular arteries, venous sinusoids, and submucosal fibers. No specific binding to submucosal glands or goblet cells was noted. Human nasal fragments secreted significantly increased amounts of RGC in response to 10 microM BK (15.0% +/- 1.8 compared with control values; mean +/- standard error of the mean; n = 7; p less than 0.01 by Student's unpaired t test), 10 microM lys-BK (12.2% +/- 3.3; n = 5; p less than 0.05), and 100 microM methacholine (35.7% +/- 2.3; p less than 0.0001). The addition of 1 microM BK, or 1 microM lys-BK, did not induce release. The addition of the BK receptor antagonist des-Arg9-[Leu8]-BK (10 microM) or inhibition of arachidonic acid metabolism with 50 microM nordihydroguaiaretic acid or 65 microM ibuprofen inhibited the prosecretory effect of 10 microM BK.(ABSTRACT TRUNCATED AT 250 WORDS)

Erythromycin inhibits respiratory glycoconjugate secretion from human airways in vitro

Erythromycin and other antibiotics have been used empirically in the treatment of patients with chronic obstructive pulmonary disease (COPD). We studied whether this empirical role of antibiotics might not be related to a possible direct effect on respiratory glycoconjugate (RGC) secretion. The effect of erythromycin on RGC secretion and hypersecretion was studied in an in vitro preparation of human airways that were secreting [3H]glucosamine respiratory glycoconjugate (RGC), and on a human endometrial adenocarcinoma cell line secreting a glycoconjugate (tumor glycoconjugate = TGC) chemically similar to the RGC secreted by the airways. Erythromycin at 10(-5) M reduced RGC secretion by 35 +/- 4% (n = 9, p less than 0.001) in both human airways and the adenocarcinoma cells, and was increasingly active in the pharmacologic range of 10(-7) to 10(-4) M. The inhibitory effect of erythromycin was maximal within 16 h and was still evident 34 h after incubation. Erythromycin was noted to reduce both spontaneous (baseline) and stimulated RGC secretion (by histamine and methacholine) from airways in culture. The blocking effect appeared to be more selective for histamine than methacholine. These effects were not associated with any toxicity to the tissues and were not associated with the inhibition of protein synthesis. Dexamethasone also inhibited RGC release in both assay systems and exhibited dose-related effects in the physiologic ranges (10(-9) to 10(-5) M). When administered together, erythromycin and dexamethasone had an additive inhibitory effect on RGC secretion (68.0 +/- 3.0%, n = 7, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Differences in innervation and secretory behaviour of two nasal glandular parts in the rat

The submucosal glands in the rat nose are characterized by the presence of both neutral and acid glycoproteins, which are important constituents of nasal and tracheobronchial secretions. This study is an attempt to gain a better insight into the secretion of these two types of glycoproteins and its neural regulation. Radiobiochemical experiments show a higher sensitivity to methacholine of the nasal glandular region producing acid glycoproteins than the area secreting neutral glycoproteins. Radioligand receptor binding suggests that the binding parameters of the muscarinic receptors in these two areas are mutually different. Furthermore, rat nasal glandular muscarinic receptors appear to be different from those in smooth muscle of rat ileum.

Cholinergic nasal hyperreactivity in atopic subjects

Increased nasal secretions are a fundamental component of allergic rhinitis. In order to analyze various parameters of nasal secretions, a relatively nontraumatic method for collecting nasal secretions was required. A small, flexible rubber catheter connected to a vacuum and inserted 4 cm into the nose proved to be an efficient method for recovering secretions produced from a series of nasal washes. An average of 67% of the washings were recovered and analyzed for protein content. Topical methacholine (5 to 100 mg) stimulated a dose-related increase in the amount of protein secreted with atopic patients demonstrating significantly more responsiveness than nonatopic patients (29.9 times the prechallenge production of protein for atopic patients and 4.8 times for nonatopic patients). Pretreatment with atropine (10 micrograms) reduced the effects of methacholine in atopic subjects, indicating that the secretory activity was in response to muscarinic receptor stimulation. Therefore, in addition to the array of autonomic abnormalities already recognized in atopic patients, these subjects are also hyperresponsive to nasal cholinergic stimulation.