Subsensitivity of T lymphocytes to sympathomimetic and cholinergic stimulation in bronchial asthma.

The effect of adrenergic and cholinergic drugs on short incubation “active” E rosette formation was studied in 19 patients with bronchial asthma and 17 healthy controls. Both groups had an equal absolute number of baseline “active” E rosettes, but the asthmatics demonstrated a higher percent baseline value. The beta adrenergic drug isoproterenol (10^?3 M) inhibited the formation of “active” E rosettes in asthmatics by only 18.0% as compared to a 60.8% inhibition in the control group. Carbamylcholine (10^?5 M) a cholinergic agonist, also showed a lower than normal response in asthmatics, 34.3% enhancement of “active” E rosetting compared to a 52.4% enhancement in the controls. The alpha adrenergic agent phenylephrine (10^?5 M) exhibited equal enhancing effects in both groups, 34.2% in the asthmatics and 36.5% in the controls. Isoproterenol (10^?3 M) had a minimal effect on inhibition of long incubation “total” E rosettes in both groups studied. The beta adrenergic abnormality conforms to the beta blockade theory of asthma of Szentivanyi. The cholinergic abnormality is unexplained in view of the hyperresponsiveness of patients with asthma to cholinergic agents in vivo. Patients with bronchial asthma probably have an autonomic dysfunction that may play a role in the pathogenesis of their disease.     

Effect of beta adrenergic agonist, prostaglandins, and cortisol on lymphocyte levels of cyclic adenosine monophosphate and glycogen : Abnormal lymphocytic metabolism in asthma

Decreased beta adrenergic regulation of cyclic adenosine monophosphate (cAMP) in lymphocytes has been described in asthma. We investigated adrenergic stimulation of glycogenolysis and responses to prostaglandin E1 (PGE1). Lymphocytes from 24 normal and 24 mild asthmatic subjects who had no drugs for at least 2 weeks were separated on Ficoll-hypaque and incubated in medium 199 with Hepes buffer. Beta adrenergic stimulation of cAMP and glycogenolysis was reduced in the asthmatics (p less than 0.05). PGE produced less of a rise in cAMP in asthmatics than in normals, but the difference was not significant (p greater than 0.05) and glycogenolysis was normal. Cortisol added in vitro potentiates the effect of isoproterenol and PGE1--but in the presence of cortisol the response of the asthmatic cells to isoproterenol is still lower than that of normal cells. This observation would support that "beta adrenergic blockade" is the major defect of asthmatic cells. The conclusion is further supported by the observation that the degree of the blockade is associated with a pathologic condition.     

Leukocytic epinephrine receptors of normal and asthmatic individuals.

To determine if the hypothesized beta adrenergic blockade in asthma is located at the level of the hormone receptor, we have compared the number and binding affinity of leukocytic epinephrine receptors in normal and asthmatic subjects. Human leukocytes, but not human erythrocytes, possess low-affinity epinephrine receptors. When saturated, each leukocyte binds approximately 1.0 times 10-6 molecules of epinephrine. Binding of 3H DL-epinephrine was largely inhibited by excess unlabeled L-epinephrine. The binding was reversible and involved both the D and L forms of 3H DL-epinephrine. Inhibition studies with nonradioactive isoproterenol, norepinephrine, propranolol, and tolazoline produced results consistent with the interpretation that the leukocytes contained both alpha and beta adrenergic receptors. Two procedures, subcellular fractionation of lymphocytes and incubation of leukocytes in 0.1 per cent trypsin, permitted the demonstration that most of the catecholamine binding occurred at the plasma membrane. Thin-layer chromatography of the bound 3H DL-epinephrine after its extraction from the leukocytes permitted the interpretation that the hormone had fully retained its chemical structure. In addition, epinephrine binding was associated with cAMP production. Leukocytic epinephrine receptors of 10 asthmatic and 9 normal individuals were compared and found not to be substantially different in number or binding affinity.     

The effect of thymoxamine and cromolyn sodium on postexercise bronchoconstriction in asthma.

Of the 22 patients with extrinsic bronchial asthma, 13 patients developed post-exercise bronchoconstriction after treadmill exercise, whereas in 9 patients treadmill exercise had no effect on the ventilatory capacity. No statistical difference in the resting lung volumes and CO transfer factor was found between the two groups. A significant inhibition of postexercise bronchoconstriction was observed in 12 of 13 patients following thymoxamine or cromolyn sodium inhalation. Inhibition of postexercise bronchoconstriction by alpha blockade with thymoxamine suggests that increased alpha adrenergic activity in the presence of diminished beta receptor responsiveness to catecholamines, norepinephrine released during exercise could have a marked alpha agonistic effect giving rise to bronchoconstriction. It has been suggested that cromolyn sodium has a cyclic phosphodiesterase inhibiting action. This might increase levels of AMP and restore the beta receptor responsiveness to catecholamines.     

Relationship between numbers of beta adrenergic receptors in lymphocytes and disease severity in asthma

In order to assess the status of beta adrenergic receptors in bronchial asthma, binding studies using (−) [³H] dihydroalprenolol (DHA) were performed on lymphocytes of 10 control subjects and 11 stable asthmatic patients. Specific DHA binding was generally lower at all DHA concentrations in asthmatics. At 12 nM DHA concentration, specific DHA binding was 391 ± 40 fM/mg protein in controls and 263 ± 35 fM/mg protein for asthmatic subjects (p < 0.05). A highly statistically significant positive correlation between specific DHA binding (at 12 nM DHA) and FEV₁/FVC% was observed (r = 0.93, p < 0.01), with those asthmatic subjects with the more severe airway obstruction and disease severity showing lower DHA binding. The results of the study suggest that a lymphocyte beta adrenergic receptor defect may be present among some patients with asthma. The magnitude of the receptor abnormality appears to be related to disease severity and degree of airway obstruction as measured by FEV₁/FVC%. Documentation of drug consumption was made, and restriction of beta adrenergic agonists was attempted; theophylline and corticosteroids were the predominant drugs used in the study. Even with these precautions, it is possible that the differences in DHA binding observed among subjects are the results of greater drug (e.g., theophylline and corticosteroids) consumption by the clinically more severe patients. On the other hand, the lymphocyte receptor alteration noted may reflect a more general beta adrenergic receptor abnormality in bronchial asthma.     

A comparison of the beta-blocking activities of practolol, sotalol, and propranolol in human and guinea pig tracheal smooth muscle

Beta adrenergic blockade was studied in vitro with hitman tracheal muscle strips and guinea pig tracheal chains. It was shown in isolated smooth muscle from both man and guinea pig that the order of potency for the three beta-blocking agents studied was: propranolol > sotalol > practolol. Under the conditions of this study, propranolol was about 30,000 times and sotalol about 30 times as potent as practolol. The order of potency suggests that the nature of adrenergic blockade induced by practolol on tracheal smooth muscle is only weakly beta₂-relative to the blocking effects of propranolol and sotalol. Beta adrenergic blockade by propranolol, sotalol, and practolol produced different degrees of increased histamine lethality in mice. Whereas both propranolol at 0.01 mg/kg and sotalol at 1.0 mg/kg resulted in 100% histamine-induced lethality, practolol at 50 mg/kg resulted in only 50% histamine-induced lethality. These data, when added to those from our previous studies, suggest that the mechanisms responsible for resistance to the effects of histamine in untreated mice are at least partially mediated by the beta₂-adrenergic system. Thus, in three different tissues, the blocking activity of practolol was shown to be less than that of sotalol or propranolol.     

Effects of beta adrenergic blockade on histamine and prostaglandin-F2 alpha responsiveness in the dog

To examine whether either the degree of existing beta adrenergic tone or the magnitude of beta adrenergic response during bronchoconstriction might account for the differences that exist between dogs in their pulmonary responsiveness to aerosol challenge with bronchoconstrictor agents, dose-response curves were performed in a group of dogs to either histamine or prostaglandin-F2 alpha, both before beta blockade with propranolol. Beta blocked had no significant effect on control values of dynamic compliance (Cdyn) or resistance of the lung (RL) or on pulmonary responsiveness to prostaglandin f2 alpha. Although propranolol did not have a significant effect on aerosol responsiveness to histamine for the group of dogs taken together, those dogs initially least responsive to aerosol histamine did become more responsive after beta blockade. This effect of beta blockade was statistically significant only for Cdyn and not for RL, suggesting enhancement of peripheral airway effects. We conclude that a beta adrenergic mechanism may contribute to the range of responsiveness found among dogs in their pulmonary responsiveness to histamine but that other as yet undefined factors must also contribute to the differences that exist among dogs in their pulmonary responsiveness to bronchoconstrictor agents.     

The effect of atropine and albuterol aerosols on the human bronchial response to histamine.

This study was designed to determine whether histamine-induced bronchoconstriction in human asthmatics is mediated by the parasympathetic nervous system and involves cholinergic pathways. Inhalation challenges were performed on 14 adult asthmatic patients using the standardized procedure for inhalation challenge recently recommended by the Asthma and Allergic Disease Centers panel. The effect of pretreatment with either aerosolized atropine sulfate or aerosolized albuterol, a specific beta-2 adrenergic agonist, was studied. The comulative units of histamine required for induction of a positive bronchial response (20% or greater drop in FEV1 from baseline) was used as the basis of comparison of the effects of these drugs. This value was expressed as the PD20-FEV1 to histamine. Analysis of the data showed that aerosolization of sufficient atropie to effect a cholinergic blockade, as shown by inhibition of the bronchial response to inhaled methacholine, only minimally affected the bronchial response to histamine (p less than 0.05). However, the administration of albuterol markedly shifted the response to histamine (p less than 0.005). Although there was a statistically significant change in the mean PD20-FEV1 to histamine following atropine blockade, this effect was small in comparison to that which could be demonstrated with a beta agonist. It would thus appear that the major influence of histamine is not through cholinergic pathways.     

Effect of inhaled lodoxamide tromethamine in prevention of antigen-induced bronchospasm

Lodoxamide tromethamine, a new cromolyn-like drug, was studied to determine its effectiveness and duration of action in preventing antigen-induced bronchospasm in 15 subjects with clinically stable extrinsic asthma. All subjects underwent antigen inhalation challenge 15 min after inhalation of an aerosolized solution of 0.1 mg of lodoxamide in saline or of saline solution alone (placebo) administered on separate days according to a double-blind, random-allocation protocol. Those subjects demonstrating a protective effect of lodoxamide subsequently underwent antigen inhalation challenges at various time intervals (2 to 8 hr) after lodoxamide treatment. Thirteen of 15 subjects (87%) showed a protective effect of lodoxamide administered 15 min prior to antigen challenge. Six of the 13 subjects who were protected initially remained protected 4 hr after lodoxamide treatment and one of these six subjects was also protected at 6 to 8 hr. One additional subject not protected at 4 hr was protected at 3 hr. Lodoxamide exhibited no bronchodilator activity and was not associated with any significant side effects. Further studies are warranted to compare the effectiveness of lodoxamide with that of cromolyn sodium in protection against antigen-induced bronchospasm and to evaluate the relative efficacy and safety of lodoxamide in long-term clinical trials.     

Prophylactic drugs in the management of childhood asthma.

Recurrences of explosive, severe asthma in children can often be prevented by immunotherapy and constant surveillance of environmental and dietary control. In addition, judicious and preserving use of pharmaceuticals may be employed for prophylaxis in childhood asthma. These include cromolyn sodium by inhalation, beclomethasone dipropionate aerosols, round-the-clock methylxanthines and beta 2 adrenergic bronchodilator agents. Their application is discussed.     

Histamine hypersensitivity in mice induced by concanavalin A

This study compared the responses of CFW and CFI mice to concanavalin A (con A) and the histamine-sensitizing factor (HSF) of Bordetella pertussis. There were marked similarities between these two agents with regard to systems implicated in induced histamine sensitivity. Con A, like HSF, induces the sensitivity in CFW but not in CFI mice. The sensitizing agents both require the same time for optimum sensitization, both induce cutaneous sensitivities to histamine, and the mice are protected from the induced susceptibility of both agents by epinephrine and by desensitization with serotonin. They differed in that con A did not induce the systemic susceptibility to serotonin or to combined histamine and serotonin which is produced by HSF. The major difference related to mechanisms of action was the failure of con A to induce a systemic beta-adrenergic blockade, the block of which is manifested in HSF-treated CFW and CFI mice by the inhibition of an epinephrine-induced hyperglycemia. The resistance of beta-blocked CFI mice to histamine, and the susceptibility to histamine of the unblocked CFW mice sensitized with con A, is inconsistent with the theory that susceptibility results from a systemic adrenergic imbalance, but does not preclude a local adrenergic effect as the common element in histamine-sensitizing agents.     

The relationship of leucocyte adenyl cyclase activity and airways response to beta blockade and allergen challenge in extrinsic asthma

Six patients with active extrinsic bronchial asthma showed a diminished leucocyte adenyl cyclase response to isoproterenol whereas seven patients in remission showed a significant increase in cyclic AMP when their cells were stimulated with isoproterenol. A significant difference in the control (basal) values of leucocyte adenyl cyclase activity between the patients with active asthma and those in remission suggests that in the active phase of asthma beta adrenergic receptors are maximally stimulated by circulating endogenous catecholamines and further stimulation with sympathomimetic amines becomes increasingly difficult. In this situation, the minor alpha receptor stimulating effect of adrenaline may become dominant and cause adrenaline reversal which is commonly observed in status asthmaticus. The leucocyte adenyl cyclase activity and its responsiveness to catecholamines did not relate to airways response induced by beta blockade or allergen challenge, nor was there any correlation between the activity of this enzyme and the total circulating reagins. These results together with the observations of reduced metabolic responses to adrenaline administration in patients with severe degree of asthma suggest that the reduced beta receptor function in asthma may reflect a failing counter-regulatory mechanism rather than be considered the cause of bronchial hyper-reactivity and atopic state in asthma. The airways response to beta blockade and allergen challenge depends on the initial or basal bronchomolor lone. The differing airways response to beta blockade in patients with extrinsic bronchial asthma and chronic bronchitis may be of clinical importance in classifying patients with obstructive airways disease.     

Nonspecific bronchial reactivity in occupational asthma

The provocative concentration (PC₂₀ mg/ml) of methacholine required to produce a fall in the baseline FEV₁ by 20% was determined in 86 patients with occupational asthma due to exposure to western red cedar, California redwood, grain dust, or isocyanates. Fifty-seven patients were assessed at the time of diagnosis when they were symptomatic. Twenty-nine patients were studied after they had been removed from exposure for a period from 2 mo to 4 yr and were asymptomatic. Nine of the 57 patients with symptomatic asthma had repeat methacholine inhalation tests after removal from exposure. The results were compared with 33 normal healthy subjects, 30 patients with nonoccupational asthma, and 17 patients with nonindustrial chronic bronchitis. Patients with symptomatic occupational asthma had marked increase in bronchial reactivity similar to those with nonoccupational asthma. The degree of hyperreactivity decreased after removal from exposure and increased following re-exposure to the offending agents. There was little overlap in the range of PC₂₀ in the asthmatic compared with the nonasthmatic groups. These findings suggest nonspecific bronchial hyperreactivity is likely to be the consequence rather than the predisposing factor in occupational asthma. Methacholine inhalation test is a simple, safe, and useful procedure in the initial assessment of patients suspected to have occupational asthma before institution of time-consuming specific bronchial provocation test.     

Comparison of cyclic adenosine monophosphate response of lymphocytes in normal and asthmatic subjects to norepinephrine and salbutamol.

Reduced response of beta adrenergic receptors, especially beta-2 receptors, has been suggested as a contributing factor in the etiology of asthma. Cyclic adenosine monophosphate (AMP) production in lymphocytes after exposure to 10(-3) M salbutamol, predominantly a beta-2 receptor stimulant, was significantly less in asthmatic subjects than in normal subjects, while there was no significant difference in cyclic AMP response to 10(-3) M norepinephrine, predominantly a beta-1 receptor stimulant. Both drugs evoked the maximum response at 10(-3) M. The cyclic AMP response to salbutamol of 5 asthmatic subjects being treated with steroids was diminished significantly compared with that of 7 patients not treated with steroids; however, the response to norepinephrine was similar in both groups. The degree of the abnormality in the beta-2 receptor response seems to be related to the severity of the asthma.     

Platelet aggregation in atopic and normal patients

Platelet aggregation was used as a model to evaluate the proposed beta blockade in subjects with allergic rhinitis and asthma. Studies using epinephrine, adenosine diphosphate (ADP), and streptococcal M protein as aggregating agents showed that there was no significant difference in platelet aggregation between atopics and controls. Furthermore, aggregation induced by all three agents was inhibited by propranolol and phentolamine, as well as by caffeine and dibutyryl cyclic adenosine monophosphate (AMP). This inhibition was evidenced with platelets from both atopics and controls. The results suggest that with platelet aggregation the atopic population taken as a whole does not differ from the normal population. Although certain atopic subjects exhibit unique aggregation patterns, pharmacologic manipulation of this system fails to document that these unique patterns are due to beta blockade.     

Nonantibiotic effects of macrolide antibiotics of the oleandomycin-erythromycin group with special reference to their “steroid-sparing” effects

Certain macrolide antibiotics, such as troleandomycin (TAO), oleandomycin, and erythromycin estolate (Ilosone), can lower the maintenance dose of glucocorticoids required by severely asthmatic patients. These effects were postulated to be caused by an as yet undefined steroid-sparing effect. In this study, TAO in combination with methylprednisolone, when compared with methylprednisolone alone, was demonstrated to significantly increase liver glycogen deposition in adrenalectomized mice, intact mice, and adrenalectomized rats; protect histamine-sensitized mice following beta adrenergic blockade or adrenalectomy; further decrease the steroid-lowered glucose tolerance of mice and significantly increase the plasma corticosteroid levels in rats. TAO alone did not have these effects. TAO plus betamethasone, and erythromycin estolate plus methylprednisolone also increased liver glycogen deposition. However, TAO did not appear to potentiate the effects of hydrocortisone. Erythromycin stearate and to a lesser degree erythromycin ethylsuccinate when combined with methylprednisolone also decreased histamine lethality in mice. Leucomycin and tetracycline did not enhance the effects of methylprednisolone. TAO, alone or with methylprednisolone, did not alter serum glutamic oxaloacetic transaminase (SGOT) levels in rats. Thus, TAO and some other macrolides did not exert their effects on corticosteroids as antimicrobial agents, adrenocorticotropic hormone (ACTH)--like compounds, or quasisteroids, but as steroid-sparing agents by some undefined mechanism.     

Papain-induced asthma—physiological and immunological features

Increasing reports of respiratory disease associated with exposure to papain prompted clinical, physiological, and immunological studies of the supervisor of a meat tenderizer factory who developed asthma after long-term contact with papain dust. His symptoms were worse at work and better on weekends and vacations. Bronchial inhalation challenges produced both immediate and late asthma to papain but not to the other ingredients in the food product. Immunological studies revealed the presence of specific IgE antibodies by direct and passive transfer skin tests and the radioallergosorbent test, and specific precipitating antibodies by immunodiffusion tests. These findings are indicative of a dual type I and III hypersensitivity. Papain acting as an allergen in an occupational setting is a risk factor for eliciting asthma even in a nonatopic individual.     

Drug-induced changes of adenylate cyclase activity in cells from asthmatic and nonasthmatic subjects.

Monolayers of adherent mononuclear leukocytes prepared from normal subjects and asthmatic children whose bronchodilater therapy did not include sympathomimetic drugs, respond to relatively low concentrations of isoproterenol (ISO) and prostaglandin E1 with increased intracellular cyclic adenosine monophosphate (cAMP) levels. The magnitude of in vitro responses to ISO is decreased by previous contact of the cells with ISO or other, orally effective, adrenergic drugs. The desensitization is rapid, concentration- and time-dependent, and is readily reversible after removal of the desensitizing drug. The phenomenon exhibits pharmacologic specificity. Cells in which the response to restimulation with ISO was decreased exhibited full sensitivity to prostaglandin E1. No differences in these behaviors were detected in cells from normal or asthmatic subjects. The results suggest that earlier observations reporting decreased responses to beta adrenergic stimulation in asthmatics may have been due to the treatment of these patients with sympathomimetic agents and not caused by a disease-related beta adrenergic receptor dysfunction.     

Trimellitic anhydride-induced airway syndromes: Clinical and immunologic studies

This report describes a spectrum of respiratory symptoms in workers exposed to trimellitic anhydride (TMA), a biologically reactive chemical used in the plastics industry. Fourteen workers who had worked on a unit which synthesized TMA were evaluated by clinical and immunologic methods. Respiratory syndromes induced by TMA inhalation included asthma and rhinitis of the immediate type, late onset asthma with systemic symptoms, and airway irritation. TMA was shown to couple rapidly to human serum albumin, forming an immunoreactive hapten-protein complex. The workers' immunologic reactivity to this complex could be quantitated and correlated with the three respiratory syndromes. The asthma-rhinitis syndrome was mediated by IgE antibody specific for the TMA hapten. The syndrome of late onset asthma with systemic symptoms was accompanied by elevated levels of TMA-specific IgG antibody. Rheumatoid factor in high titer was found in one worker with IgE-mediated asthma and in two workers with asthma of late onset. Lymphocyte reactivity of TMA-HSA was demonstrated in three workers representative of the three clinical syndromes. Leukocyte histamine release was demonstrated to TMA-HSA in one worker with high levels of IgE antibody specific for TMA-HSA who had severe symptoms of acute rhinitis and asthma.     

Correlation between increased bronchial responsiveness to histamine and diminished plasma cyclic adenosine monophosphate response after epinephrine in asthmatic children. Diminished plasma cyclic adenosine monophosphate response after epinephrine in moderate childhood asthma.

The respiratory threshold to histamine and the plasma cyclic adenosine monophosphate (AMP) every 5 min for 40 min after subcutaneous epinephrine were determined in 21 children with moderate bronchial asthma who were without symptoms at the time of study. There was a statistically significant correlation between a high respiratory sensitivity to histamine and a low plasma cyclic AMP response to epinephrine. The plasma cyclic AMP response was compared with that in 16 control subjects. The asthmatic patients had significantly diminished responses; the difference was greatest for the values 25 min after stimulation. This study supports the hypotheses that the bronchial hyperresponsiveness in asthma is due partly to a defective beta adrenergic system and that the defect is permanent, existing also during periods without symptoms or medication and in patients with moderate asthma.