Alveolar macrophage-derived chemotactic factor: kinetics of in vitro production and partial characterization.

Alveolar macrophages are the initial phagocytic cells that encounter foreign material and particulates deposited in the terminal airways. We have examined a mechanism by which these cells, after phagocytic challenge, may control or amplify the inflammatory response in lung parenchyma. Normal human alveolar macrophages (AM) were studied from eight subjects. With in vitro culture, AM produced and released two substances into culture media which have potent chemoattractant activity for blood polymorphonuclear granulocytes (PMN) and negligible activity for mononuclear cells. Release of these factors is maximally stimulated by aggregated human immunoglobulin (Ig)G or zymosan particles; however, simple adhesion of the macrophages to plastic surfaces is also sufficient to stimulate release of these chemotactic substances. The larger substance (10,000 daltons) is immunologically distinct from C5a and interacts with a different PMN membrane receptor than that known to exist for formyl-methionyl-leucyl-phenylalanine. Its chemotactic activity is sensitive to the enzymatic effect of trypsin. Although producing a single elution peak on gelfiltration chromatography, electrofocusing in polyacrylamide gels yielded five peaks of radioactivity. Chemotactic activity was localized to a fraction with a pI = 5.0. The smaller molecular weight substance has been less well characterized. Thus, the human AM can produce at least two factors which attract PMN and this capability may augment the local inflammatory response in the lung.

Physician practice variation in assignment of return interval.

BACKGROUND: Recent shifts in reimbursement toward capitation makes appointment availability a significant resource and stimulates us to understand primary care physician (hereafter referred to as "provider") behavior concerning appointment assignment. The results of prior studies suggest significant provider variability in this area. OBJECTIVE: To examine the influences on assigning patient revisit intervals in the ambulatory setting. METHODS: Survey regarding general care issues of hypothetical diabetic and hypertensive patients seen in an ambulatory setting was given to 62 providers in the Internal Medicine Program at the Tulane University Internal Medicine Residency Program and outpatient clinics, New Orleans, La. Measurements evaluated included survey responses for demographics (sex, year of birth, year of graduation from medical school, and level of training) and practice style (decision to change therapy, order tests, and recommended return appointment interval in weeks) variables. RESULTS: The response rate was 89% (56 providers). Most respondents were men (n = 39). Wide variation was noted in assignment of reappointment interval with mean return intervals for the scenarios ranging from 2.2 to 20.5 weeks. Significant influences on provider practice included patient stability (P<.001), the decision to change therapy (P = .001), and the decision to order tests (P = .001). All correlated with an earlier return appointment. Some providers exhibited test-ordering tendencies across scenarios. Sex was a significant provider independent variable and was not influenced by other study variables. Female providers assigned earlier reappointment intervals for their patients. CONCLUSIONS: Wide variation exists among practitioners with similar training background and practice setting. As expected, patient stability was a major determinant of assigned return interval. Test-ordering behaviors may consume appointments inappropriately and may be a productive area for efforts to reduce provider variability. The influence of the provider's sex on scheduling follow-up appointments warrants further investigation.

Proteins of the respiratory tract after heart-lung transplantation.

Heart-lung transplant recipients represent a unique population who experience episodic lung injury caused by infection or rejection. We hypothesized that the proteins in the respiratory lining fluids of these patients might reflect and provide insights into the in vivo immunologic and inflammatory events that occur in the transplanted lung. Structural, inflammatory, and immune proteins were quantitated in 57 samples of BAL fluid recovered from 17 heart-lung recipients when infections, rejection, or neither was present. Protein levels were compared with those of normal subjects and between the clinical transplant groups. When neither infection nor rejection was present, levels of albumin, fibronectin, and immunoglobulins G, M, and A were all higher in the transplanted lungs as compared with the normal lungs. These findings suggest that a new steady state of these proteins is established in the transplanted lungs. When infection or rejection was present, there was a further significant increase in albumin, fibronectin, IgG, and especially C5a in the transplanted lungs. These findings suggest that at least some elements of host defense remain intact in the posttransplantation period despite the use of immunosuppressive drugs and a HLA-incompatible microenvironment. The profiles of recovered alveolar proteins did not, however, help to differentiate infection from rejection. This is disappointing because distinguishing between infection and rejection without examination of lung tissue remains an unresolved and important clinical problem. Nevertheless these data provide new insights into organ tolerance and defense of the newly transplanted lung from infection or rejection.

Biologic activity of purified cotton bract extracts in man and guinea pig.

Purified aqueous extracts of cotton bract induce acute airway constriction in healthy volunteers never before exposed to cotton bract. The response is similar to that of textile workers who inhale cotton dust. Approximately 60% of volunteers respond to bract extract with significant decreases in lung function, and these volunteers show an increased number of lymphocytes present in their lungs. Following inhalation of bract, the percent of polymorphonuclear leukocytes increases. Macrophages obtained by bronchoalveolar lavage from volunteers pre-challenged with bract extract release increased amounts of chemotactic factor and superoxide anion. Efforts to detect release of histamine and leukotrienes in volunteers following challenge with bract show no increase in urinary histamine and no significant release of leukotrienes in lung lavage fluid. Purified extracts exhibit chemotactic activity in vitro. They also contract guinea pig ileal longitudinal muscle in vitro. This preparation contains mast cells but no basophils, and the H-1 blocker, mepyramine blocks the contraction. Purified bract extracts contain no histamine or endotoxin but other contractors of smooth muscle may be present. The purified extract exhibits spectral, fluorescent, and radioimmune assay properties similar to a leukotriene B-like component. Cotton bract appears to have direct as well as cell-mediated activities.

Association between neutrophil concentration in bronchoalveolar lavage fluid and recent losses in diffusing capacity in men formerly exposed to asbestos.

It has been observed widely that some individuals exposed to asbestos will experience continued losses of lung function after asbestos exposure ceases. Unfortunately, there are few data on factors that determine clinical course, limiting the clinician's ability to determine prognosis in an individual case and restricting the possibility for testing or targeting any potential intervention to alter the course among the millions at risk. In an attempt to address this question, we studied a volunteer population of 50 such men from among a stable, heterogeneous population of asbestos-exposed workers who had been continuously followed in our occupational medicine clinics for up to 12 years (mean, 6.3 years); most had some clinical or roentgenographic sign of asbestos effect, pleural or parenchymal. Each subject was reexamined clinically, functionally, and roentgenographically. Asbestos and tobacco exposure histories were carefully reviewed with the subjects and quantified based on these reports and available data regarding the various work environments from which they came. Subsequently, each underwent a bronchoalveolar lavage to assess cellularity and levels of various proteins. The levels of risk factors, clinical findings, and biologic parameters from lavage were examined for their relationship to serial changes in lung function during the period over which they had been previously followed. Results of the study demonstrate that serial changes in lung function were not closely related to level or length of prior exposure, smoking behavior, chest roentgenographic findings, or lung volumes. Progressive loss of diffusing capacity for carbon monoxide (Dco) was significantly associated with two factors: level of neutrophil concentration in lavage fluid (0.043 +/- 0.016 ml/min/mm Hg/yr drop for each 0.1 x 10(4) neutrophils per milliliter, p = 0.02) and the level of Dco itself (0.17 +/- 0.07 ml/min/mm Hg/yr drop for each 10 percent decrease in percent Dco predicted, p = 0.01). The relationship with neutrophil concentration was statistically independent of the association with Dco itself and stronger; it persisted when loss of Dco was adjusted for baseline value. Lung volume changes were not associated with any predictor variables, alone or in combination. We conclude that the presence of neutrophils in bronchoalveolar lavage fluid is associated with recent disease progression that may have implications in studies of the mechanisms of asbestos-associated disease and in clinical treatment of patients at risk.

The relationship between large airway inflammation and airway metaplasia.

To assess the role of acute inflammatory cells in large airways in the pathogenesis of metaplasia, we performed BAL (divided into aliquots) and mucosal biopsies on asbestos workers. They had evidence of asbestos-related lung injury. We found that acute inflammatory cells were significantly increased in the first aliquot. Ex-smokers had a greater percentage of PMN compared with nonsmokers and current smokers. The subjects were subgrouped with respect to biopsy-detected metaplasia. There was no difference between these groups for percentage or total number of PMN in the first aliquot. However, subjects with metaplasia had significant reduction in FEV1/FVC compared with those without. We conclude that there are significant differences in cells between the first and subsequent aliquots. Although inflammatory stimuli may be important in the pathogenesis of metaplasia, PMN present in the first aliquot could not be related to the severity of the metaplastic changes in these workers.

Relationship of the ventilatory response to cotton bract extract and the cells and proteins of the lung.

Many healthy subjects who have had no exposure to cotton textile dusts will experience significant reductions in expired flow rate following an inhalational challenge with an aqueous extract of cotton bracts (CBE). Differences noted among individuals in the magnitude of the bronchial response to a standardized preparation of CBE suggest variable airway reactivity. The mechanism of this response and the reasons for its variability among these naive subjects are unknown. We have studied this problem by performing bronchoalveolar lavage on 13 volunteer subjects with no history of textile dust exposure. Two to three months later, a bronchial provocation with aqueous CBE was performed by an investigator blinded to the lavage results. Subjects with greater than 20 percent drop in flow rate at 40 percent of vital capacity during a partial forced expiration (MEF 40 percent [P]) following CBE had a reduction in total recoverable alveolar macrophages, with a resultant increase in the percentage of recoverable lymphocytes. The magnitude of response (MEF 40 percent [P]) correlated directly with the measured lymphocyte percentage (r = 0.69 p less than 0.01) and inversely with the total numbers of recovered cells.

Association between acute inflammatory cells in lavage fluid and bronchial metaplasia.

In epidemiologic studies, airway disease and parenchymal injury are known morbid outcomes of occupational exposure to asbestos. However, the relationship of inflammatory events considered to be responsible for parenchymal injury to the subsequent development of airway injury is unknown. To assess this we performed bronchoalveolar lavage (BAL) and airway biopsies on a population of subjects with exposure to asbestos in the workplace. As an index of airway injury, we employed histologic metaplasia seen in mucosal biopsy specimens. Lung BAL fluid was analyzed for two potentially relevant protein markers and for inflammatory cells recovered from the lower respiratory tract. We related metaplasia to demographic features of this study population (eg, smoking history and asbestos exposure data) and also to the protein and cellular markers recovered by BAL. We studied 50 workers and detected keratinizing metaplasia in 15 and varying lesser abnormalities in the other 28. Cigarette smoking was not associated with the presence of metaplasia (p less than 0.2). Smoking status was associated with an increase in BAL cells (p less than 0.02); however, neither the percent nor concentration of acute inflammatory cells was significantly increased. Acute inflammatory cells (percent and cells per milliliter of BAL fluid) were significantly increased among the subjects with severe metaplasia compared with other study subjects. This increase was true of both neutrophils and eosinophils and the sum of these two (p less than 0.02). Stratification of subjects by smoking status demonstrated a persistent association of inflammatory cells with metaplasia. By logistic regression analysis, polymorphonuclear leukocytes per milliliter and eosinophils per milliliter were significantly related to the presence of metaplasia in two independent models (odds ratios, 9.9 and 7.6, respectively). Cigarette smoking and other demographic or BAL variables were not significantly associated with metaplasia in these models.

Respiratory infection complicating long-term tracheostomy. The implication of persistent gram-negative tracheobronchial colonization.

Colonization of the lower respiratory tract by enteric Gram-negative bacilli (EGNB) has been a frequent finding in patients with long-term tracheostomies; however, the association of hospitalization and certain features of serious illness with this phenomenon has not been clearly established. Because such factors can render the oropharynx more susceptible to EGNB colonization, we sought to discover whether they can also have this effect on the tracheobronchial tree and its microflora. Thus, we collected serial paired culture samples from these two mucosal sites in 15 subjects with long-term tracheostomies and examined patterns and rates of colonization and related these findings to clinical parameters. In 49 sets of cultures, we found that EGNB (especially Pseudomonas species) were present in significantly fewer upper-airway cultures (36.7 percent) than lower-airway cultures (75.5 percent) (p = 0.009). At the tracheobronchial site, seven subjects had persistent EGNB colonization, all with Pseudomonas species, while only one subject had this finding at the oropharyngeal site (p = 0.015). Patients with persistent tracheobronchial colonization were more ill than those without this finding. They were treated with higher doses of prednisone (p = 0.06), received antibiotics more often, and developed purulent tracheobronchitis more often (100 percent vs 25 percent) than patients without persistent colonization. In addition, in the month following the culture survey, four subjects developed pneumonia, and three of these had previous persistent tracheobronchial colonization.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulation of endoperoxide product levels and cyclophosphamide-induced injury by glutathione repletion.

Glutathione is a tripeptide important in a number of diverse cellular functions including enzymatic reactions involved in prostaglandin endoperoxide metabolism. We have previously reported that cyclophosphamide administration to rats results in acute lung injury manifested by increased bronchoalveolar lavage albumin concentrations. In the current study we examine whether cyclophosphamide treatment affects pulmonary glutathione stores or bronchoalveolar endoperoxide metabolic product levels and whether these effects may be related to acute lung injury caused by the drug. We show that cyclophosphamide treatment causes a dose-dependent reduction in pulmonary glutathione stores 4 h after drug administration. In addition, acute lung injury as the result of cyclophosphamide can be abrogated by coadministration of oxothiazolidine carboxylate, an intracellular cysteine delivery system that also reverses pulmonary glutathione depletion induced by cyclophosphamide in our study. Finally, cyclophosphamide treatment reduces prostaglandin E2 concentrations in bronchoalveolar lavage and alveolar macrophage culture supernatant in a dose-dependent fashion and increases bronchoalveolar thromboxane concentrations in low dose-treated animals. These effects are reversed to a variable degree by coadministration of oxothiazolidine carboxylate. Our study suggests in vivo pulmonary arachidonic acid metabolism and cyclophosphamide-induced acute lung injury are modulated by cellular glutathione stores. These findings may have important implications for the treatment of acute lung injury.

Bronchoalveolar cell activation after inhalation of a bronchoconstricting agent.

Airway inflammation is thought to be an important determinant of bronchoconstriction and bronchial hyperreactivity. We have recently demonstrated that bronchoconstriction induced by an aqueous extract of cotton bracts (CBE) is associated with bronchoalveolar complement activation, release of polymorphonuclear neutrophil (PMN) chemoattractants by pulmonary cells, and increased numbers of bronchoalveolar lavage PMN's. In the present study we performed bronchoalveolar lavage (BAL) on subjects after CBE or control (saline) challenge and examined whether BAL cells were activated in vitro to produce other inflammatory agonists. After CBE administration, cultured BAL cells released increased amounts of the reactive O2 species, superoxide (O2-.), and the cyclooxygenase products prostaglandin E2 and thromboxane B2. Although none of these in vitro parameters of BAL cell activation appeared to correlate with the degree of bronchoconstriction induced by CBE, BAL fluid levels of thromboxane B2 were also increased after CBE administration and in vivo amounts of this eicasanoid did correlate with the degree of bronchoconstriction induced by CBE (r = 0.50, P less than 0.04). Finally, although cell culture supernatants were highly chemotactic for PMN's, concentrations of leukotriene B4 were not increased, suggesting other chemotaxins were released by BAL cells in this setting. We conclude that CBE administration activates bronchoalveolar cells to release reactive O2 species and cyclooxygenase products that may be important in the bronchoconstricting response to CBE.

Effect of Fluosol-DA/O2 on the antitumor activity and pulmonary toxicity of bleomycin.

The effect of an oxygen-carrying perfluorochemical emulsion on bleomycin antitumor activity and pulmonary toxicity was examined. Fluosol-DA (0.3 ml/mouse, i.v.), combined with bleomycin (10 or 15 mg/kg, i.p.) and a 2 h exposure to 95% oxygen (BFO) increased by five- to six-fold the tumor growth delay of FSaIIC fibrosarcoma compared to bleomycin alone (B). Only a slight increase in tumor growth delay was noted with the incomplete combinations of bleomycin and O2 (BO) and bleomycin and Fluosol-DA (BF). When bleomycin (10 mg/kg) was co-administered with 0.3 ml Fluosol-DA and 95% O2, cell survival was reduced ten-fold compared to that seen with bleomycin alone. In contrast, the surviving fraction of cells obtained from FSaIIC tumors treated in vivo indicated that 0.3 ml Fluosol-DA per mouse or a 2 h exposure to 95% O2 did not markedly alter the effects of bleomycin alone. The pulmonary effects of the BFO combination were assessed during the course of the therapy by bronchoalveolar lavage (BAL) analysis and pulmonary hydroxyproline (OH-Pro) content. Mice treated with this combination had a 20-fold increase in total numbers of cells obtained in the BAL compared to control animals. An increased cellularity in the lungs was also seen morphologically. The composition of the cells in the lavage fluid was altered after BFO but not BO treatment and reflected a neutrophilic influx. Furthermore, total protein recovered in the BAL fluid was increased 5-fold in the BFO treatment group compared to that in the control mice. Pulmonary OH-Pro, an index of collagen and fibrosis, was unaffected acutely after three treatments of either BFO or BO compared to control mice. Thus, Fluosol-DA and O2 can enhance the antitumor activity of bleomycin. The increased pulmonary cellularity suggests that this combination may also have adverse effects on lung tissue.

Radiation-induced lung injury.

The use of radiation therapy is limited by the occurrence of the potentially fatal clinical syndromes of radiation pneumonitis and fibrosis. Radiation pneumonitis usually becomes clinically apparent from 2 to 6 months after completion of radiation therapy. It is characterized by fever, cough, dyspnea, and alveolar infiltrates on chest roentgenogram and may be difficult to differentiate from infection or recurrent malignancy. The pathogenesis is uncertain, but appears to involve both direct lung tissue toxicity and an inflammatory response. The syndrome may resolve spontaneously or may progress to respiratory failure. Corticosteroids may be effective therapy if started early in the course of the disease. The time course for the development of radiation fibrosis is later than that for radiation pneumonitis. It is usually present by 1 year following irradiation, but may not become clinically apparent until 2 years after radiation therapy. It is characterized by the insidious onset of dyspnea on exertion. It most often is mild, but can progress to chronic respiratory failure. There is no known successful treatment for this condition.

Cigarette smoking and respiratory tract infection.

Although not conclusive, several lines of evidence suggest that cigarette smoking alters the respiratory tract's ability to defend itself from infection. Some subjects with chronic bronchitis have colonization of the lower respiratory tract with bacteria. Both patients with chronic respiratory disease and healthy smokers appear to have a higher frequency of respiratory infections and an increased severity of symptoms when infected. Children exposed passively to cigarette smoke have higher rates of respiratory illnesses. Yet the marked variability in the incidence of infection in the smoking population suggests that there are subtle factors that predispose some smokers to more risk of infection than others. Cigarette smoking is associated with alterations in mechanisms of the host defense system, even in asymptomatic individuals (summarized in Table 3). Ciliary function is impaired, mucous volume is increased, humoral response to antigens altered, and quantitative and qualitative changes in cellular components occur. Some of these alterations in host defense mechanisms are dose related; others revert to normal after smoking cessation. Yet, it is unknown if one or all of these alterations cause any significant compromise of host defense or if other factors, as yet unidentified, may be important. Answers to these questions await a more thorough elucidation of normal host defense function.

Interstitial lung diseases in the elderly patient.

In this article we have attempted to review basic aspects of the respiratory immune system and some of what is known about the effects of aging on immunity. We have discussed the more common forms of interstitial lung disease as they relate to the elderly patient and have outlined a general method of approaching interstitial disease in this population. This topic is the focus of considerable ongoing research, and a wealth of information is available for the clinician who desires to delve more deeply into the subject. It is our hope that this article will serve as a background to facilitate further study by those with a particular interest in this area.