Immunologic studies in allergen-induced late-phase asthmatic reactions

We have measured plasma histamine, serum neutrophil chemotactic activity (NCA) and complement (C3 and C4) over a 24-hour period in patients experiencing either early- and late-phase (dual) or single early asthmatic reactions to inhaled allergens. There was a significant biphasic elevation in plasma histamine, which paralleled the fall in forced expiratory volume in 1 sec in 10 patients with dual responses, whereas in seven subjects with single early reactions, only a single early increase in histamine concentrations was observed. In general, in the individual subjects, the changes in plasma histamine paralleled both the elevations in serum NCA and the decreases in forced expiratory volume in 1 sec. By gel filtration on Sephacryl S-400, anion exchange chromatography on DEAE Sephacel, and chromatofocusing with Polybuffer Exchanger 94, the major NCA of both the early and the late reactions was associated with proteins having an estimated molecular size of 600,000 daltons, an elution from DEAE Sephacel at 0.15M to 0.30M of NaCl (pH 8.1), and a pI of approximately 6.5. There were no appreciable changes in serum C3 and C4 up to 24 hr after challenge in subjects with late-phase responses. The patterns of asthmatic response were not related to either the total or allergen-specific serum IgE or IgG4 concentrations. These results support the view that mediators of hypersensitivity participate in late-phase as well as early asthmatic reactions.

Preferential generation of leukotriene C4 by human eosinophils

The leukotriene generating capacities of ionophore stimulated human eosinophils and neutrophils were compared using specific radioimmunoassays for LTB4 and LTC4. Mixed granulocyte preparations (neutrophils and eosinophils) produced both LTB4 and LTC4 in a time-dependent fashion which was maximal at 10 and 15 min, respectively. Following the separation of eosinophils (greater than 75%) and neutrophils (greater than 90%) by metrizamide gradients, LTC4 production was predominantly from eosinophils, whereas neutrophils were the principal source of LTB4. The concentrations of leukotrienes produced by the eosinophil and neutrophil rich cell preparations were directly proportional to the concentration of ionophore. Following purification of eosinophil derived products by RP-HPLC the LTC4 immunoreactivity corresponded to the elution profile of a synthetic LTC4 marker. Furthermore, in 32 atopic subjects (21 bronchial asthmatics and 11 non-asthmatics) the amounts of LTC4 produced by unseparated leucocytes were directly proportional to the percentage of eosinophils in the total cell suspension. Preferential generation of LTB4 by neutrophils was also demonstrated by immunoreactivity of ionophore stimulated supernatants subjected to RP-HPLC, as well as by its characteristic u.v. absorbance and GC-MS profile and the ability to promote directional neutrophil locomotion (chemotaxis). These experiments support the concept that eosinophils accumulate in tissues partly as a result of the response to neutrophil derived LTB4, and that these cells contribute to the production of sulphidopeptide leukotrienes with subsequent amplification of the acute allergic response.

Migration of retained pacemaker electrodes

Two cases of migration of retained pacemaker electrodes are described. The first presented as an unusual cause of deep vein thrombosis while the second was asymptomatic and detected by routine chest x-ray. Both made a good recovery, the first with surgery and the second with the fragment left in situ. A review of the world literature revealed only 13 other such cases. Of the total of 15 cases four are known to have died. In these patients no relationship was found between morbidity and the site of migration or associated infection and/or thrombosis. However surgical treatment appeared to be associated with a better prognosis.

Do oral and inhaled terbutaline have different effects on the lung?

The effect of inhaled or oral terbutaline on the subsequent response to inhaled terbutaline was studied using a double-blind cross-over technique in 12 asthmatic patients. 12 indices of respiratory function were obtained from the maximal flow-volume loop and a single-breath inert gas technique. These were used to evaluate the effect and to attempt to distinguish the site of action of the drug. Although the initial dose of inhaled terbutaline had a greater immediate effect than its oral counterpart there were no significant differences in the response to subsequently inhaled terbutaline. These findings do not support recent suggestions that oral administration has a greater effect on distal airways or promotes the effects of inhaled bronchodilators.