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The purpose of this study was to determine the relative contributions of airway wall edema and smooth muscle contraction to the early response (ER) of allergic bronchoconstriction. Brown Norway rats, 6 to 7 wk old, were sensitized with ovalbumin (OA). Anesthetized rats were challenged with either OA or saline 2 wk later. Pulmonary resistance (RL) was measured every minute until either it increased to 150% of the baseline, defined as a significant ER, or until 15 min elapsed. Eight OA-challenged test rats with a significant ER and eight saline-challenged control rats were used for morphometric studies. The lungs were quick-frozen with liquid nitrogen, processed with freeze substitution, and sagittal sections (5 microns) were stained with hematoxylin and eosin. The airway lumen subtended by the epithelial basement membrane (LuB) and cross sectional airway wall area (AW) of all airways were measured by camera lucida and digitization. The LuB and AW of each airway was standardized for size by dividing by the ideal airway lumen (LuBideal), which was calculated from the length of basement membrane, assuming a perfect circle in the unconstricted state. The cumulative frequency distribution of the LuB/LuBideal for the airways from test rats was shifted to the left compared with the control rats (p less than 0.01), indicating airway narrowing after challenge. Airway narrowing increased as a function of airway size. Cumulative frequency distributions of AW/LuBideal showed that there was a significant increase in the wall thickness of only the small airways of test animals.(ABSTRACT TRUNCATED AT 250 WORDS)

To evaluate the hypothesis that lymphocyte stimulation can modify the bronchoconstrictive response to inhalational challenge with an allergen, we administered interleukin-2 (IL-2), an important lymphokine in lymphocyte activation and proliferation, to actively sensitized rats. Brown Norway rats received either human recombinant IL-2 (n = 8) or its vehicle (n = 7) twice a day from the ninth to the fourteenth day after active sensitization to ovalbumin (OA) and were challenged with an aerosol of OA. Lung resistance (RL) during the early response increased to a maximum of 698 +/- 230% and 180 +/- 26% of baseline values in the animals receiving IL-2 and vehicle, respectively (p less than 0.025). The late response was threefold greater in IL-2-treated than in vehicle-treated animals (p = 0.01). IL-2 increased OA-specific IgG levels in the serum, but it did not significantly affect total or specific IgE levels. IL-2 caused an inflammatory infiltrate around the airways with significant increases in eosinophils, lymphocytes, and mast cells prior to antigen challenge. Our results indicate that stimulation of cell-mediated immunity can affect airway responsiveness to antigen.

The purpose of this study was to evaluate the possible role of the quantity of airway smooth muscle (AWSM) as a determinant of differences in responsiveness between inbred rat strains. To do this, we studied several batches of 8- to 10-wk-old Lewis and Fisher 344 rats. Animals were anesthetized intraperitoneally with pentobarbital (30 mg/kg) and xylazine (7 mg/kg). The peak value of pulmonary resistance (RL) was measured after progressively doubling concentrations of inhaled aerosolized methacholine (MCh). The MCh concentration required to double RL (EC200RL) was calculated as an index of airway responsiveness. Fisher rats were significantly more responsive than Lewis, and the interstrain variability in responsiveness was significantly greater than the intrastrain variability. Additional animals from the less responsive Lewis strain (n = 8) and the more responsive F344 strain (n = 11) were killed immediately after measurement of responsiveness, and AWSM was quantitated as a fraction of total lung tissue using a point-counting technique. F344 rats were again significantly more responsive than Lewis rats (EC200RL geometric mean: 0.72 versus 2.16 mg/ml, p less than 0.005). F344 rats also had significantly more AWSM than did Lewis rats (3.22 +/- 0.176 versus 2.48 +/- 0.185%, mean +/- SE, p less than 0.001). We conclude that highly inbred Fisher rat strains characteristically exhibit a degree of airways responsiveness greater than that of the Lewis strain and that the quantity of AWSM may be an important determinant of interstrain differences.

The purpose of this study was to quantitate the structural changes in the airways of sensitized rats after repeated challenge with aerosolized antigen and to examine the relationship between these changes and alterations in responsiveness to methacholine (MCh). We studied 28 Brown Norway rats that were actively sensitized to ovalbumin (OA). Responsiveness to aerosolized MCh was quantitated as the concentration of MCh required to double pulmonary resistance (EC200 RL). The EC200 RL was determined before and 1 and 5 days after three inhalational challenges with OA (n = 17) or saline (n = 11) at 5-day intervals (on Days 14, 19, and 24 after sensitization). Responsiveness to MCh increased after OA; EC200 RL fell from 1.71 to 0.71 mg/ml at 1 day (p less than 0.01) and 0.87 mg/ml at 5 days (p less than 0.02) after OA but did not change after saline challenge. Formalin-fixed lungs from a sample of OA-challenged (n = 12) and saline-challenged (n = 6) animals were paraffin embedded, and 5-microns sections were stained with hematoxylin-phloxin-saffron. Cross-sectional areas of the airway wall and smooth muscle (ASM) were determined for all intrapulmonary membranous airways. There was an approximately twofold increase in the quantity of airway smooth muscle in airways of OA-challenged animals compared with saline-challenged control animals. Airway wall area did not change significantly. There was a correlation (r = 0.618, p less than 0.05) between the quantity of ASM in large airways (basement membrane length 2.00 to 2.99 mm) and change in responsiveness to MCh.

We evaluated the potential role of the lymphocyte in chronic airway inflammation and responsiveness by repeated administration to rats of interleukin-2 (IL-2), the principal lymphokine responsible for lymphocyte proliferation. Lewis rats (mean weight, 184 +/- 2 g) received either 120,000 units of IL-2 (n = 10) or vehicle (n = 7) subcutaneously twice a day for 4.5 days. Animals were anesthetized with urethane and intubated for measurements of pulmonary resistance (RL) and airway responsiveness to aerosol methacholine (MCh). Lung lavage was performed, the animals were exsanguinated, and the lungs were fixed in 10% formalin. Histologic edema and the extent of infiltration of the bronchi, pulmonary veins, and arteries by cells was scored blindly. IL-2 increased airway responsiveness to MCh; the concentrations of MCh causing a doubling of RL were 0.14 versus 1.39 mg/ml (geometric mean) for the IL-2 and vehicle group, respectively (p = 0.001). IL-2 significantly increased total cellular return and the percentage of lymphocytes, neutrophils, and eosinophils in lavage. IL-2 caused edema and a mixed cellular infiltration of the bronchovascular tree. Lymphocytes predominated around the airways and veins. A correlation (r = 0.50) was present between airway responsiveness and airway inflammation but not with edema or vascular infiltration. Release of IL-2 by lymphocytes in the airways may be an important mediator of airway hyperresponsiveness.

We studied the acute effects of interleukin-2 (IL-2), the principal lymphokine responsible for lymphocyte proliferation, on lung mechanics and airway responsiveness to methacholine (MCh) in rats. Lewis (n = 12) and Fisher 344 (n = 13) rats were anesthetized and intubated, and intravenous and intra-arterial lines were inserted. IL-2 (750,000 U/kg) was infused intravenously over 2 to 4 min into seven Lewis and seven Fisher rats, and vehicle alone was administered to five Lewis and six Fisher rats. Blood pressure, heart rate, respiratory frequency (f), tidal volume (VT), minute ventilation (VE), and lung resistance (RL) were measured before and every 5 min for 45 min after the infusion of IL-2. Lung compliance was measured before and 30 min after IL-2. Bronchial provocation testing with MCh was performed 45 min after the infusion of IL-2. Subsequently, the animals were exsanguinated, and the lungs were removed for histologic examination. Infused IL-2 did not alter heart rate or blood pressure, VT, f, VE, and RL increased significantly by 15 min (p less than 0.05), but they returned to baseline by 45 min. Lung compliance decreased significantly in both rat strains. IL-2 increased airway responsiveness only in Lewis rats; the concentration of MCh that caused a doubling of RL (EC200RL) was 0.6 mg/ml and 4.3 mg/ml (p = 0.003) in IL-2-treated and control rats, respectively. The airway responsiveness did not change significantly in Fisher rats; EC200RL was 0.13 and 0.35 mg/ml for IL-2-treated and control rats, respectively (p = 0.09).(ABSTRACT TRUNCATED AT 250 WORDS)

To quantitate the structural changes in the airways that contribute to the late bronchial response (LR) to antigen challenge we killed six Brown-Norway rats, sensitized to ovalbumin (OA) and challenged by aerosol, during the LR and compared the dimensions of the intraparenchymal airways with those of six control animals. Lungs were rapidly frozen with liquid nitrogen and fixed in Carnoy's solution. Paraffin sections were stained with hematoxylin-phloxine-saffron. At the time of the LR (382 +/- 39 min after OA challenge), RL increased from the baseline value (0.067 +/- 0.034 cm H2O.ml-1.s) by 0.107 +/- 0.03 cm H2O.ml-1.s (p less than 0.05). RL did not change significantly in the control rats. The lumen size and the wall area of all membranous airways were measured and were corrected for airway size by dividing by the basement membrane length squared (BM2). There was no increase in airway wall area in OA-challenged animals. However, the lumen of large airways (BM: 2.0 to 2.99 mm) was significantly less for the OA-challenged animals (0.039 +/- 0.0055 mm2) than for the control animals (0.058 +/- 0.0063 mm2; p less than 0.05). In six additional rats, the distribution of mast cells (MC) in the bronchial tree was determined. Tissues were fixed with Carnoy's solution and stained with a modified May-Grunwald-Giemsa stain. There were significantly more MC in the large airways than in medial or small airways. We conclude that smooth muscle constriction of large airways and not airway wall edema accounts for the LR in the rat. The distribution of the mast cells corresponds closely to the site of bronchoconstriction.

Inflammatory cells are believed to play an important role in the pathogenesis of emphysema; however, a relationship between presence of cells in the lung parenchyma and its destruction has never been shown. The aim of this study was to quantitate alveolar septal cellularity in smokers' lungs and to investigate its relationship with parenchymal destruction and lung function. The lungs of 23 smokers (SS) undergoing thoracotomy for localized pulmonary lesions were compared with those of eight nonsmokers (NS) and five smokers (AS) who died suddenly of nonrespiratory causes. Pulmonary function tests were performed within 1 wk of surgery in SS. For each subject, we quantitated alveolar wall cells (CELLS), an index of alveolar wall destruction (DI), and the mean linear intercept (Lm). As no significant differences were found between S and AS with regard to these indices, we combined them (Group S) for comparison with NS. Although Lm was not significantly different between S and NS, (0.331 +/- 0.072 versus 0.288 +/- 0.038), CELLS and DI were higher in S than in NS (48 +/- 8 versus 25 +/- 2 cells/mm, p less than 0.001; 47 +/- 20 versus 17 +/- 5, p less than 0.001, respectively). Further, CELLS and DI were significantly correlated (r = 0.799, p less than 0.001). The number of polymorphonuclear cells (PMN) in S can exceed that in NS by as much as 5-fold; however, PMN were inversely correlated with parenchymal destruction (DI) (r = 0.598, p less than 0.01). Thus, smokers' lungs have alveolar septal hypercellularity, possibly inflammatory, and closely related to destruction involving cells other than the PMN.

Destruction of alveolar walls is considered by most observers to be the most important part in the definition of emphysema, yet it has never been precisely defined and quantitated. We therefore attempted to devise a reliable microscopic technique to quantitate alveolar destruction that would be both sensitive to disease and easy to perform. Using a point-count system, we obtained an index of parenchymal destruction that represents the percentage of destroyed space as a fraction of the total alveolar and duct space. We have called this measurement the destructive index (DI). In the lungs of 8 nonsmokers and 23 smokers, we quantitated the DI and compared it with the mean linear intercept (Lm) and with pulmonary function in smokers. Although Lm was not significantly different in the 2 groups, significant differences between the DI of smokers and nonsmokers (p less than 0.005) were found. In addition, the DI correlated with FEV1(-0.43, p less than 0.05), MMEF (r = -0.44, p less than 0.05), and recoil pressure at 90% TLC (r = -0.61, p less than 0.05) in smokers. These findings suggest that the destructive component of emphysema can be easily quantitated microscopically, occurs in smokers before dimensional changes are evident (i.e., increased Lm), and influences lung function. Therefore, the quantitation of this destruction (DI) could add greatly to the microscopic definition of emphysema, complementing the information given by the dimensional component of emphysema (Lm).

Elastic fibers are fairly uniform in the size around all alveolar orifices and taper and branch continuously in the alveolar wall to form a spiderweb-like structure. Unusually large gaps of the elastic fiber network in the alveolar wall frequently show coiled ends or tissue debris at the margin. The latex-filled capillaries interweave and intersect with the elastic fibers and in many of these places appear to angulate or narrow acutely; these angulations may alter with lung inflation, affecting pulmonary vascular resistance. Disruption of fine elastic fibers in the alveolar wall could be related to the development of pulmonary emphysema.

The recognition of bronchioloalveolar carcinoma (BAC) as distinct from adenocarcinoma of the lung, is controversial. Using strict pathologic criteria, 43 consecutive patients with BAC were matched by year of diagnosis and compared with a similar number of patients with adenocarcinoma, and for contrast, with those with squamous and oat cell carcinoma of the lung. We demonstrated that BAC is not sex related, and is not as smoking related as the other neoplasms. Unlike epidermoid carcinoma, BAC does not show a predilection for those occupations requiring manual labor. Also, BAC is frequently distinguishable radiologically from the other three by being smaller and peripheral. A pleural tag and an air bronchogram in a mass are rather specific, and BAC is less likely to have large airway involvement and adenopathy. The percentage of patients who were free of tumor after 2 yr was greater in the BAC group than in the others, but the overall survival rate between the BAC group and the adenocarcinoma group was not. Based on inter-observer variability, there is some overlap pathologically between these 2 groups. However, when the overlap between the adenocarcinoma and the BAC groups is compared with that between the adenocarcinoma and the squamous cell carcinoma groups, the difference is not significant. We conclude that BAC should be considered a distinct clinical entity.

We studied post-mortem 9 nonsmokers' lungs and 9 smokers' lungs as well as 14 surgical smokers' lungs to examine the possible relationship of the number of alveolar attachments with airways inflammation and with lung function. Alveolar attachments are the alveolar walls radially attached to the small airways, and any discontinuity or rupture of these alveolar walls was considered abnormal. Normal and abnormal attachments were counted in nonsmokers and smokers and expressed as number of attachments, distance between attachments, and percentage of abnormal attachments. Although internal small airways diameter and mean linear intercept were not significantly different between smokers of either group and nonsmokers, significant differences in number of attachments (p less than 0.001), distance between attachments (p less than 0.01), and percentage of abnormal attachments (p less than 0.01) were found. The 3 indexes of alveolar attachments correlated significantly with the score for airways inflammation and with the elastic recoil pressure in smokers. No significant correlation with any other lung function test was found. We conclude that smokers have fewer alveolar attachments than do nonsmokers, and that the loss of alveolar attachments represents an early stage in the destruction of lung parenchyma, and is probably linked to inflammation of the small airways. Because of the strategic situation of this lesion, it could be responsible in part for the loss of elastic recoil seen in the initial stages of chronic obstructive pulmonary disease.

We studied 12 smokers' lungs with scanning electron microscopy in order to analyze the distribution and size of alveolar fenestrae and their relationship to the average distance between alveolar walls (Lm) and lung function. Alveolar fenestrae in areas near terminal airways (respiratory bronchioles and alveolar ducts) were consistently larger than fenestrae far from airways (alveoli). Fenestrae in near areas increased in size as Lm increased (r = 0.845, p less than 0.001), whereas no correlation between Lm and fenestrae size in far areas was found (r = 0.281, NS). The overall area of fenestrae (near and far) correlated significantly with FEV1 (r = -0.745, p less than 0.01), MMEF (r = -0.752, p less than 0.01), and PL90 (r = -0.804, p less than 0.05). However, when subdivided into near and far, only fenestrae near the small airways showed a significant correlation with function. These findings suggest that in smokers with mild to moderate emphysema, destruction affects preferentially the areas around the terminal airways (near areas), and these changes, although small, might play an important role in the lung function.

Some investigators feel that the lingula should be avoided as a site of open lung biopsy because of the assumed prevalence of nonspecific changes. We sought to judge the validity of the lingular biopsy by examining specimens of the lingula and left lower and right upper lobes from 50 consecutive unselected autopsies. Sections were stained with hematoxylin-eosin and Masson's trichrome and were examined for the extent of fibrosis, pulmonary vascular changes, and acute and chronic inflammation. Using both a morphometric and a semiquantitative grading system (r = 0.80), we noted that both fibrosis and pulmonary vasculopathy were more evident in the lingula than in either of the 2 other lung segments (p less than 0.05 ANOVA, Newman-Keul test). There was no difference between the lingula and other segments for either acute or chronic inflammation (p greater than 0.10), and there was no difference in any of the morphologic parameters between the right upper and left lower lobes (p greater than 0.10). We conclude that the lingula shows nonspecific changes and thus may not be a valid biopsy site.

Lympatics in the parietal pleura and diaphragm of rabbits and mice formed lacunas, terminal dilatations of lymphatic channels, with cribriform laminas bordering the pleural space at one end and one-way valves on the other end. The laminas consisted of a coarse mesh of connective tissue fibers covered by mesothelial cells at one side and endothelial cells at the other. At the fenestrated portions of the meshwork the basal surfaces of the 2 lining cells were closely apposed and some preformed stomas were found bridging the pleural and lymphatic spaces. No such structures were found in the visceral pleura, but similar cribriform laminas were also present in human parietal pleura at autopsy. Intrapleurally injected carbon particles reached the lacunas faster than similarly injected chicken red blood cells in living rabbits. Carbon particles appeared to pass through the closely apposed lining cells as well as the stomas but not into the intact interstitial structures. These structural and functional findings supported the observation that large particles and cells in the pleural cavity are removed only through the lymphatics and only at specific sites in the parietal pleura.