Local Pulmonary Immune Response Research Articles

Local Pulmonary Immunological Biomarkers in Tuberculosis.

Regardless of the eventual site of disease, the point of entry for Mycobacterium tuberculosis (M.tb) is via the respiratory tract and tuberculosis (TB) remains primarily a disease of the lungs. Immunological biomarkers detected from the respiratory compartment may be of particular interest in understanding the complex immune response to M.tb infection and may more accurately reflect disease activity than those seen in peripheral samples. Studies in humans and a variety of animal models have shown that biomarkers detected in response to mycobacterial challenge are highly localized, with signals seen in respiratory samples that are absent from the peripheral blood. Increased understanding of the role of pulmonary specific biomarkers may prove particularly valuable in the field of TB vaccines. Here, development of vaccine candidates is hampered by the lack of defined correlates of protection (COPs). Assessing vaccine immunogenicity in humans has primarily focussed on detecting these potential markers of protection in peripheral blood. However, further understanding of the importance of local pulmonary immune responses suggests alternative approaches may be necessary. For example, non-circulating tissue resident memory T cells (TRM) play a key role in host mycobacterial defenses and detecting their associated biomarkers can only be achieved by interrogating respiratory samples such as bronchoalveolar lavage fluid or tissue biopsies. Here, we review what is known about pulmonary specific immunological biomarkers and discuss potential applications and further research needs.

MERS‐CoV infection is associated with downregulation of genes encoding Th1 and Th2 cytokines/chemokines and elevated inflammatory innate immune response in the lower respiratory tract

MERS‐CoV, a highly pathogenic virus in humans, is associated with high morbidity and case fatality. Inflammatory responses have a significant impact on MERS‐CoV pathogenesis and disease outcome. However, CD4+ T‐cell induced immune responses during acute MERS‐CoV infection are barely detectable, with potent inhibition of effector T cells and downregulation of antigen presentation. The local pulmonary immune response, particularly the Th1 and Th2‐related immune response during acute severe MERS‐CoV infection is not fully understood. In this study, we offer the first insights into the pulmonary gene expression profile of Th1 and Th2‐related cytokines/chemokines (Th1 & Th2 responses) during acute MERS‐CoV infection using RT2 Profiler PCR Arrays. We also quantified the expression level of primary inflammatory cytokines/chemokines. Our results showed a downregulation of Th2, inadequate (partial) Th1 immune response and high expression levels of inflammatory cytokines IL‐1α and IL‐1β and the neutrophil chemoattractant chemokine IL‐8 (CXCL8) in the lower respiratory tract of MERS‐CoV infected patients. Moreover, we identified a high viral load in all included patients. We also observed a correlation between inflammatory cytokines, Th1, and Th2 downregulation and the case fatality rate. Th1 and Th2 response downregulation, high expression of inflammatory cytokines, and high viral load may contribute to lung inflammation, severe infection, the evolution of pneumonia and ARDS, and a higher case fatality rate. Further study of the molecular mechanisms underlying the Th1 and Th2 regulatory pathways will be vital for active vaccine development and the identification of novel therapeutic strategies.Support or Funding InformationThe authors thank the Research Center at King Fahad Medical City for funding this study (Grant No 017‐066).

MERS-CoV infection is associated with downregulation of genes encoding Th1 and Th2 cytokines/chemokines and elevated inflammatory innate immune response in the lower respiratory tract

MERS-CoV, a highly pathogenic virus in humans, is associated with high morbidity and case fatality. Inflammatory responses have a significant impact on MERS-CoV pathogenesis and disease outcome. However, CD4+ T-cell induced immune responses during acute MERS-CoV infection are barely detectable, with potent inhibition of effector T cells and downregulation of antigen presentation. The local pulmonary immune response, particularly the Th1 and Th2-related immune response during acute severe MERS-CoV infection is not fully understood. In this study, we offer the first insights into the pulmonary gene expression profile of Th1 and Th2-related cytokines/chemokines (Th1 & Th2 responses) during acute MERS-CoV infection using RT2 Profiler PCR Arrays. We also quantified the expression level of primary inflammatory cytokines/chemokines. Our results showed a downregulation of Th2, inadequate (partial) Th1 immune response and high expression levels of inflammatory cytokines IL-1α and IL-1β and the neutrophil chemoattractant chemokine IL-8 (CXCL8) in the lower respiratory tract of MERS-CoV infected patients. Moreover, we identified a high viral load in all included patients. We also observed a correlation between inflammatory cytokines, Th1, and Th2 downregulation and the case fatality rate. Th1 and Th2 response downregulation, high expression of inflammatory cytokines, and high viral load may contribute to lung inflammation, severe infection, the evolution of pneumonia and ARDS, and a higher case fatality rate. Further study of the molecular mechanisms underlying the Th1 and Th2 regulatory pathways will be vital for active vaccine development and the identification of novel therapeutic strategies.

Disorders of local pulmonary immune response in patients with chronic obstructive pulmonary diseases during exacerbation

Introduction. Morbidity due to reduced local immune reaction in patients affected by chronic obstructive pulmonary disease (COPD) is extremely high and continues to grow. The results of a research on changes in the local immune response in patients with COPD at the exacerbation stage are discussed in this paper. The pathogenesis of COPD during exacerbation is characterized by deterioration of the local innate and acquired immunity. The process is accompanied by pathological changes of the systemic immunity. Various cells of the immune response are involved in the inflammation process, attracting increased amounts of macrophages, neutrophils, T- and B-lymphocytes, and dendritic cells. The number of neutrophils and B-lymphocytes are observed in patients suffering from a severe disorder. Most common symptoms of COPD are irreversible narrowing of the airways, destruction of the parenchyma of the lung accompanied by emphysema, and progression of the obstructive pulmonary disease. The aim of the study – to learn the changes in functionality of bronchoalveolar lavage (BAL) cells and peripheral blood cells (PBC) in COPD patients and provide an explanation for these changes in light of pathogenetic characteristics to predict the course of the disease and justify the necessity of a local immunotherapy in comprehensive treatment of COPD patients. Research Methods. The focus of the research was on BAL cells and PBC of patients with COPD at different stages and on blood serum. CD3, CD4, CD8, CD16 and CD19 of BAL and PBC cells were identified using different specific monoclonal antibodies. Receptor expression to IL-2 (CD25) was examined, adhesive molecules were identified using CD54, proliferation levels were measured using IPO-38, as well as was measured the expression of class II antigens MHC (HLA-DR) in the blast transformation reaction that was induced by PHA and Con A mitogens. Phagocytic activity of phagocytizing neutrophils cells, alveolar macrophages (AM), and phagocytizing PBC cells was evaluated. Levels of free radical processes and antioxidant defence were studied using a chemiluminescence method. Results and Discussion. The amount of AM cells in COPD patients declined significantly, whereas the amount of neutrophils notably increased, as well as concentrations of the myeloperoxidase and the eosinophil cationic protein. Examination of phlegm and BAL cells obtained from COPD patients at the exacerbation stage of the disease indicate that 23 % of samples displayed gram-negative bacterial flora (primary pathogens being Pseudomones aeruginosa, Haemophillus influensae, Enterobacter spp.), 15 % – candidas, 61 % – pathogen type was not identified. Researching local and systemic immune response in COPD patients and functional activity changes of BAL and PBC indicated that patients showed significant changes in their local immune system, which manifested in significant reduction in the amount of neutrophils in the lavage, reduction in CD3, CD19, and increased expression of receptors to HLA-DR antigen expression. Summary. Parallel study of the local and systemic immunological responses contributes to expand our knowledge and understanding of pathogenesis of COPD. It is useful in determining methods to help decrease the number of complications and aid in COPD prophylaxis in persons of working age. It also provides information on which local immunotherapy will prove to be most effective. Exploring the subject further should provide fundamental understanding of similar and different symptoms of various disorders in patients with inflammation processes at the local immune level in different body locations, such as respiratory organs during COPD, in the peritoneal cavity during peritonitis, dermal lesions or any other changes in the local immune system of a different body location.

Local pulmonary immune responses in domestic cats naturally infected with Cytauxzoon felis

Cytauxzoonosis is a hemoprotozoal disease of cats and wild felids in the South and Southeastern United States caused by Cytauxzoon felis. Although the causative agent has been recognized since the seventies, no study has examined the local immune response in affected organs, such as the lung, and compared them to the lungs of uninfected domestic cats. Previous studies have suggested that the histopathologic findings in the lungs of C. felis-infected cats are caused by the release of pro-inflammatory mediators, such as cytokines and increased production of inducible nitric oxide synthase (iNOS), by the infected macrophages. Our laboratory had previously found an upregulation of the adhesion molecule CD18, which can stimulate the release of these pro-inflammatory mediators. The objective of this study was to characterize local pulmonary immune responses in cats naturally infected with C. felis. Immunohistochemistry was performed to detect tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, iNOS, and major histocompatibility complex (MHC) II in 19 lungs from affected cats that died between 2005 and 2013. Results showed increased expression of all of these molecules when compared to lungs from uninfected, healthy cats. Furthermore, MHC II is expressed in the endothelium of C. felis naturally infected cats. These results support that there is a marked, local, pro-inflammatory immune response that can contribute to the pathogenesis of cytauxzoonosis in the lungs.

Imbalance of M1/M2 alveolar macrophages phenotype in bronchial asthma (LB506)

This study evaluated imbalance of M1/M2 alveolar macrophages (AM) phenotype in BA of various state and healthy volunteers (HV). Methods: In bronchoalveolar lavage fluid (BALF) and culture medium of AM in patients with intermittent BA (iBA) (n=15, 46,56±4,18 y.o.), persistent BA (pBA) (n=15, 48,24±3,27 y.o) and HV (n=10, 51,83±3,52 y.o.) AM phenotype was assessed by flow cytometry (Beckman Coulter FC500) by production of proinflammatory M1 cytokines: IL‐1β, IL‐8, IL‐12p70, IFN‐γ, TNF‐α and TNF‐β; anti‐inflammatory М2 cytokines: IL‐4, IL‐5 and IL‐10, and bivalent М1/М2 cytokines: IL‐2 and IL‐6. Results: Analysis of BALF cytokine profile in iBA and pBA identified evident imbalance of pulmonary immune response towards M2 phenotype as compared to HV. Generalized M1/M2 indices in iBA and pBA were comparable ‐ 0.84 and 0.88. The value of M1/M2 index in healthy persons was assumed equal to 1. Genuine AM phenotype assessed by cytokine production in culture medium revealed significant changes in BA regardless of the disease state. In both iBA and pBA M1/M2 indices changed towards M1 vs. HV (4.68 and 1.59, respectively). Conclusions: Analysis of cytokine pattern in bronchoalveolar lavage fluid and culture medium of alveolar macrophages in bronchial asthma revealed imbalance of M1/M2 alveolar macrophages phenotype and local pulmonary immune response. Shift of genuine alveolar macrophages phenotype towards M1, probably, reflect common proinflammatory component of the disease and contribute to asthma exacerbation. Drift of cytokine pattern in BALF towards M2 phenotype most likely indicate compensatory reaction of alveolar macrophages and of the innate immune response.

Inflammatory and apoptotic alterations in serum and injured tissue after experimental polytrauma in mice

The exact alterations of the immune system after polytrauma leading to sepsis and multiple-organ failure are poorly understood. Thus, the early local and systemic inflammatory and apoptotic response was characterized in a new polytrauma model and compared with the alterations seen after single or combined injuries. Anesthetized C57BL/6 mice were subjected to either blunt bilateral chest trauma (Tx), closed head injury, right femur fracture including contralateral soft tissue injury, or a combination of injuries (PTx). After 2 hours or 6 hours, animals were sacrificed, and the systemic as well as the local pulmonary immune response (bronchoalveolar lavage [BAL]/plasma cytokines, lung myeloperoxidase [MPO] activity, and alveolocapillary barrier dysfunction) were evaluated along with lung/brain apoptosis (lung caspase 3 Western blotting, immunohistochemistry, and polymorphonuclear leukocytes [PMN] Annexin V). Hemoglobin, PO2 saturation, and pH did not differ between the experimental groups. Local BAL cytokines/chemokines were significantly increased in almost all groups, which included Tx. There was no further enhancement of this local inflammatory response in the lungs in case of PTx. At 2 hours, all groups except sham and closed head injury alone revealed an increased activity of lung MPO. However, 6 hours after injury, lung MPO remained increased only in the PTx group. Increased BAL protein levels were found, reflecting enhanced lung leakage in all groups with Tx 6 hours after trauma. Only after PTx was neutrophil apoptosis significantly decreased, whereas lung caspase 3 and plasma interleukin 6/keratinocyte chemoattractant (KC) were substantially increased. The combination of different injuries leads to an earlier systemic inflammatory response when compared with the single insults. Interestingly, only after PTx but not after single or double hits was lung apoptosis increased, and PMN apoptosis was decreased along with a prolonged presence of neutrophils in the lungs, which may therefore represent a possible pathomechanism for lung injury after polytrauma.

Immunopathogenesis of porcine reproductive and respiratory syndrome in the respiratory tract of pigs

Porcine reproductive and respiratory syndrome (PRRS) virus (PRRSV) impairs local pulmonary immune responses by damaging the mucociliary transport system, impairing the function of porcine alveolar macrophages and inducing apoptosis of immune cells. An imbalance between pro- and anti-inflammatory cytokines, including tumour necrosis factor-α and interleukin-10, in PRRS may impair the immune response of the lung. Pulmonary macrophage subpopulations have a range of susceptibilities to different PRRSV strains and different capacities to express cytokines. Infection with PRRSV decreases the bactericidal activity of macrophages, which increases susceptibility to secondary bacterial infections. PRRSV infection is associated with an increase in concentrations of haptoglobin, which may interact with the virus receptor (CD163) and induce the synthesis of anti-inflammatory mediators. The balance between pro- and anti-inflammatory cytokines modulates the expression of CD163, which may affect the pathogenicity and replication of the virus in different tissues. With the emergence of highly pathogenic PRRSV, there is a need for more information on the immunopathogenesis of different strains of PRRS, particularly to develop more effective vaccines.

Association between sputum smear status and local immune responses at the site of disease in HIV-infected patients with pulmonary tuberculosis

Infection with human immunodeficiency virus (HIV) may affect the clinical presentation of pulmonary tuberculosis (TB). To investigate the association between sputum smear status at presentation and local pulmonary immune responses in HIV-infected patients with pulmonary TB, we compared the cellular and cytokine profiles in bronchoalveolar lavage (BAL) fluid obtained from the site of lung disease in 22 sputum smear- and culture-positive, and 17 sputum smear-negative but culture-positive pulmonary TB patients. Smear-positive patients had significantly higher BAL fluid concentrations of IL-6 (p=0.007), IL-8 (p=0.02), IL-10 (p=0.03) and IFN-gamma (p=0.008) than smear-negative patients. No significant differences in the proportions of examined BAL cells were found. We concluded that sputum smear-positive TB was associated with greater pro-inflammatory and immunomodulatory cytokine responses at the site of lung disease than sputum smear-negative disease. The local immune responses may affect the clinical presentation of active pulmonary TB in HIV-infected patients.

Pulmonary T H2 response in Pseudomonas aeruginosa–infected patients with cystic fibrosis

Pseudomonas aeruginosa infection determines the course of cystic fibrosis (CF) lung disease. Studies in human peripheral blood indicate that P aeruginosa infection is associated with a predominant T(H)2 immune response, whereas T(H)1 responses are accompanied by a better pulmonary outcome. Analyses of peripheral blood may not correspond directly with the local pulmonary immune response. Therefore, we asked whether the T(H)1/T(H)2 response is altered in bronchoalveolar lavage fluid from P aeruginosa-infected patients with CF. Bronchoalveolar lavage fluid was obtained from 12 patients with CF chronically infected with P aeruginosa, 11 noninfected patients with CF, and 8 healthy controls. Pulmonary CXCR3(+) (T(H)1) and CCR4(+) (T(H)2) expressing CD4(+) and CD8(+) lymphocytes were quantified by flow cytometry. Levels of T(H)1-associated (IL-2, IFN-gamma, IFN-gamma inducible T cell-alpha chemoattractant, Monokine induced by IFN-gamma, IFN-gamma inducible protein of 10 kd) and T(H)2-associated (IL-4, IL-5, IL-10, thymus and activation-regulated chemokine [TARC], macrophage-derived chemokine) cytokines and chemokines and a panel of proinflammatory molecules were quantified at the protein level. Chemokines mRNA levels were assessed by real time RT-PCR. P aeruginosa-infected patients with CF had significantly higher levels of pulmonary CCR4(+)CD4(+) (T(H)2) cells, IL-4, IL-13, and TARC and lower levels of IFN-gamma compared with noninfected patients with CF and healthy controls. Bronchoalveolar lavage fluid levels of IL-4, IL-13, and TARC correlated inversely with FEV(1) in P aeruginosa-infected patients with CF. These results reveal the prevalence of a pulmonary T(H)2 immune response in P aeruginosa-infected patients with CF. The modulation of the pulmonary T(H)2 response in P aeruginosa infection may be an option for the treatment of P aeruginosa lung disease in patients with CF.

Comparison of the quality of protection elicited by toxoid and peptide liposomal vaccine formulations against ricin as assessed by markers of inflammation

Ricin is a very toxic substance which inhibits protein synthesis and produces severe tissue damage and inflammation. It is very potent when inhaled as an aerosol and protection has been examined in a series of studies using vaccine candidates including a formaldehyde inactivated ricin toxoid and the A chain of ricin, a polypeptide equivalent to half of the toxin molecule. Initially, subcutaneous injections of both compounds were found to protect against inhaled ricin but not without some subsequent adverse signs. Intra-pulmonary vaccination using liposomal formulations of these compounds was investigated with a view to improving lung condition following challenge. Using the humoral and local pulmonary immune responses as indices of vaccine performance, no significant difference between toxoid or peptide vaccines was found. In the third and current study, the quality of lung protection by vaccines was assessed using markers of inflammation. Thus, the profiles of inflammatory cell and protein influx into the lung were determined following intratracheal (i.t.) challenge with ricin of rats treated with liposomal vaccine formulations. Results showed that liposomal ricin toxoid offered a better quality of protection with a significantly lower influx of polymorphonuclear leucocytes (neutrophils) and little pulmonary oedema compared with the A chain/liposome formulation. Further, there was no significant difference between the quality of protection offered by the A chain when administered subcutaneously or locally into the lung by i.t. instillation. Liposomal ricin toxoid is a good candidate vaccine and optimised pulmonary delivery by inhalation should be further examined.

Formulation of the purified fusion protein of respiratory syncytial virus with the saponin QS-21 induces protective immune responses in [formula omitted] mice that are similar to those generated by experimental infection

The feasibility of employing a vaccine composed of the purified fraction 21 of Quillaja saponaria (QS-21) and the fusion (F) protein of respiratory syncytial virus (RSV) to induce protective immune responses in the lower respiratory tract of Balb c mice was examined. Our goal was to compare local and systemic immune responses with those induced following immunization with the protein adsorbed to aluminium hydroxide ( F ALOH ) adjuvant or by experimental infection. Sera from mice vaccinated with the QS-21 formulation ( F QS-21 ) contained elevated anti-F protein IgG antibody titres that were dependent on the dose of QS-21 employed. Similar to the immune responses generated by experimental infection, the sera from mice vaccinated with F QS-21 possessed greater capacity to neutralize virus infectivity that was associated with the generation of heightened complement-fixing IgG2a antibody titres. In contrast, vaccination with F ALOH elicited systemic immune responses that were characterized by a predominance of protein-specific antibodies of the IgG1 subclass and lower neutralizing antibody titres. The capacity of F QS-21 to facilitate local pulmonary immune responses was also examined and found to be similar to those induced by experimental infection. After virus challenge, a 90-fold increase in the number of F protein-specific antibody-secreting cells was observed and associated with the clearance of virus from the infected lungs. Moreover, elevated levels of antigen-dependent killer cell activity were detected and appeared to be mediated by class I major histocompatibility complex restricted CD8+ T cells. Additional characterization of the pulmonary immune response was performed on the cellular infiltrates obtained after bronchoalveolar lavage and on formalin-fixed lung tissue. The local protective immune responses induced after challenge of the groups immunized with F QS-21 or infectious virus were significantly different from those elicited in naive control mice injected with adjuvant alone, or in mice immunized with F ALOH . The cellularity of the lavage fluids from the former groups was characterized by a significantly greater percentage of lymphocytes and less neutrophils. In similar fashion histological evaluation of the lungs from mice immunized with F QS-21 or infectious virus revealed significantly elevated local immune responses after challenge. In conclusion, the results suggest that formulation with F QS-21 alters the qualitative and quantitative nature of the immune response to the F glycoprotein when compared with the traditional aluminium-based adjuvants.

Influenza virus host resistance models in mice and rats: utilization for immune function assessment and immunotoxicology

Each year influenza viruses are responsible for epidemic respiratory diseases with excess morbidity and mortality. The severity of influenza disease ranges from mild upper respiratory tract infections to severe lower respiratory tract infections involving pneumonia, bronchiolitis and coincidental bacterial super-infections. The immune response to influenza viruses can be schematically divided into a cascade of non-specific and specific functions. These functions are involved at different well defined time points after infection. We describe in this manuscript three influenza models utilized in our laboratory: (i) a highly virulent influenza virus (influenza A/Hong Kong/8/68 (H3N2) virus) adapted to B6C3F1 mice, (ii) a mouse-adapted influenza A/Port Chalmers/1/73 (H3N2) virus, and (iii) a rat-adapted influenza virus (RAIV) model (influenza A/Port Chalmers/1/73 (H3N2)). This rat-adapted influenza model has been mainly utilized as a model to assess local immunotoxic effects of inhaled environmental pollutants such as phosgene. These host resistance models are also useful for assessing the effect of systemically-induced immunosuppression or immunomodulation by drugs or chemicals on the local pulmonary immune response to influenza virus. The comparison of these different models allowed two major conclusions: (a) viral replication and mortality are two different endpoints and are not necessarily linked (no mortality was observed with Port Chalmers virus in the mouse although the virus replicates to high titers in the lung with a kinetic pattern comparable to the one obtained with Hong Kong virus), (b) mortality, viral replication, and immune function assessment are different endpoints that can be used, depending on the question addressed.

Bronchoalveolar Lavage in Alcoholic Liver Cirrhosis: T-Lymphocyte Subsets and Immunoglobulin Concentrations

The purpose of this study was to determine the phenotype profiles of immune effector cells and the concentrations of immunoglobulins in the lower respiratory tract of nonsmoking patients with alcoholic liver cirrhosis (ALC). Nine nonsmoking patients with liver biopsy-proved ALC (grade B or C cirrhosis in Child's classification), free of clinical pulmonary symptoms, and with normal chest roentgenogram were included in the study. The control group included 12 healthy nonsmokers. Each patient had fiberoptic bronchoscopy with bronchoalveolar lavage (BAL). The number of T cells and of lymphocyte subpopulations was determined by immunofluorescence studies using monoclonal antibodies that were specific for CD3, CD4, and CDS markers. Patients with ALC exhibited a dramatically increased percentage of CD8⁺ cells in BAL that induced a low CD4/CD8 ratio (0.96 ±0.15 vs 1.8 ±0.12 in healthy controls). Further characterization of lymphocyte subsets' dual immunofluorescence analysis demonstrated that most of the CD8⁺ alveolar lymphocytes had a phenotype of cytotoxic cells (CD8⁺ CD11b⁻; 48 percent ± 13 in ALC vs 10 percent ± 5 in controls). ALC was associated with an appreciable alveolar-capillary "leak" as demonstrated by a significant increase in BAL fluid albumin. In addition, the concentrations of immunoglobulins in BAL fluid were significantly greater in ALC than in controls. However, the relative (to albumin) coefficient of excretion of IgC, A, and M in and cvmacroglobulin BAL fluid was not significantly different between controls and ALC. Our results indicate that increased proportions of CB8⁺ and especially of CD8⁺ CD11b⁻ cells are a common feature in the lower respiratory tract of nonsmoking patients with ALC. These changes may be of potential functional importance in the regulation of the local pulmonary immune response in ALC.

Characterization of murine lung dendritic cells: similarities to Langerhans cells and thymic dendritic cells.

Dendritic cells (DC) are potent accessory cells (AC) for the initiation of primary immune responses. Although murine lymphoid DC and Langerhans cells have been extensively characterized, DC from murine lung have been incompletely described. We isolated cells from enzyme-digested murine lungs and bronchoalveolar lavages that were potent stimulators of a primary mixed lymphocyte response (MLR). The AC had a low buoyant density, were loosely adherent and nonphagocytic. AC function was unaffected by depletion of cells expressing the splenic DC marker, 33D1. In addition, antibody and complement depletion of cells bearing the macrophage marker F4/80, or removal of phagocytic cells with silica also failed to decrease AC activity. In contrast, AC function was decreased by depletion of cells expressing the markers J11d and the low affinity interleukin 2 receptor (IL-2R), both present on thymic and skin DC. AC function was approximately equal in FcR+ and FcR- subpopulations, indicating there was heterogeneity within the AC population. Consistent with the functional data, a combined two-color immunofluorescence and latex bead uptake technique revealed that lung cells high in AC activity were enriched in brightly Ia+ dendritic-shaped cells that (a) were nonphagocytic, (b) lacked specific T and B lymphocyte markers and the macrophage marker F4/80, but (c) frequently expressed C3biR, low affinity IL-2R, FcRII, and the markers NLDC-145 and J11d. Taken together, the functional and phenotypic data suggest the lung cells that stimulate resting T cells in an MLR and that might be important in local pulmonary immune responses are DC that bear functional and phenotypic similarity to other tissues DC, such as Langerhans cells and thymic DC.

Pulmonary Immune Response of Dogs after Exposure to239PuO2

This study evaluated the cell-mediated (CMI) and humoral immune responses in four Beagle dogs five to six years after single inhalation exposures to different monodisperse 239PuO2 aerosols (0.72-1.4 microns activity median aerodynamic diameter). These exposures resulted in initial lung burdens ranging from 19 to 35 kBq. Four nonexposed dogs were used as age-matched controls. Anesthetized dogs were immunized by instillation of sheep red blood cells (SRBC) into selected lung lobes. Cells and fluids were obtained serially from blood samples and by bronchoalveolar lavage of the saline- and SRBC-treated lung lobes at 5-20 days after immunization. The CMI response evaluated by the leukocyte procoagulant activity test was similar in the saline- and SRBC-treated lobes of both groups of dogs. The humoral immune response was measured by the enzyme-linked immunosorbent assay. No differences were shown between the amount of antibody measured in the sera or lung lavages from control or Pu-exposed dogs. Histopathology of the tracheobronchial lymph nodes from the Pu-exposed dogs showed them to be fibrotic with no lymphoid cells, suggesting that these tissues could not respond to the antigen deposited in the lungs. However, both mediastinal and sternal lymph nodes did contain lymphoid tissue, and were likely to be the lymphoid tissues that produced the immunity to the antigen deposited in the lungs of the exposed dogs. Although both exposed and control dogs produced immune responses to the antigen instilled into their lungs, differences were observed in the number of neutrophils in lung lavages from the control and exposed animals. There was a dramatic influx of neutrophils into both the saline- and SRBC-treated lung lobes of the Pu-exposed dogs that was not seen in the age-matched controls. This suggests that the inhaled 239PuO2 produced chronically-active inflammation in the lung which may contribute to recruitment of lymphocytes to the lung following intrapulmonary deposition of antigen. In conclusion, the immune responses induced by lung immunization of dogs that had inhaled 239PuO2 were not suppressed by large doses of chronic alpha irradiation of the lungs and tracheobronchial lymph nodes, indicating that local pulmonary immune responses are preserved despite severe radiation-induced alteration of these tissues.

Use of bronchoalveolar lavage to compare local pulmonary immunity with the systemic immune response of Toxocara canis-infected mice.

Following infection of mice with larvae of the canine roundworm Toxocara canis, there is a persistent pneumonitis. Heretofore, nothing was known about the immunologic potential of the cells that constitute this inflammatory exudate. By performing bronchoalveolar lavage (BAL), enough inflammatory cells were obtained to compare the local pulmonary immune response to T. canis infection with the systemic immune response as reflected in the peripheral blood and spleen cells of the same mice. Groups of C57BL/6J female mice were given 100 infective ova and BAL, peripheral blood, and spleen cells collected on days 8, 11, 14, and 17 postinfection. The percentage of eosinophils in the BAL averaged about 80% and was four to five times as great as that in the peripheral blood at all times assayed. Use of concanavalin A (ConA)-elicited lymphocyte blastogenesis to evaluate T-lymphocyte activity revealed that BAL T-cell activity was low on day 8 and peaked on day 11. When the B-cell mitogen lipopolysaccharide was used in the assay, there appeared to be far less BAL cell reactivity compared with BAL T-cell activity. Both B- and T-cell responses of the BAL cells were only a fraction of the responses seen concurrently in spleen cells. Use of Toxocara exoantigens in the blastogenesis assay revealed that Toxocara exoantigens could elicit between 20 and 95% of the ConA response in BAL cells, while in spleen cells Toxocara exoantigens could only elicit 1 to 5% of the ConA response. These results suggest that BAL is a useful method for recovering local inflammatory cells that possess detectable immunologic activity. In the case of pulmonary toxocariasis, eosinophils account for the majority of the cells that are present, with most of the remaining cells being T. canis antigen-specific T lymphocytes.

Splenic influence on the development of a local pulmonary immune response.

The role of the spleen in the development of specific antibody-forming cells (sAFC) in the pulmonary draining lymph nodes (pdLNC) of hamsters after local inoculation of sheep erythrocytes (SRBC) was evaluated. The role of the spleen was viewed from two vantage points. Panels of animals were either splenectomized with appropriate sham-operated controls before intratracheal inoculation of SRBC, or panels were immunized intravenously simultaneously with the local inoculation of antigen. The presence of an intact spleen was not necessary for the induction of a sAFC response to occur in the pdLNC. Similar numbers of immunoglobulin M (IgM) sAFC were recorded in the pdLNC on day 4 of both sham-operated and splenectomized animals. However, an enhancement of this local response occurred on day 7 if the animals were systemically immunized and therefore demonstrated active participation of the spleen in the specific immune response. The results support the hypothesis that although a local response may occur in the pdLFC in the absence of a spleen or a splenic response, the presence of a systemic or splenic response appears to be important for the enhancement of local IgM sAFC response. These observations suggest that the immune defenses involved in the lower respiratory tract may differ from those in upper respiratory tract and other mucosally lined organs in that the response of the spleen to the antigen affects the local response to that antigen.

Immunopathogenesis of hypersensitivity pneumonitis

This review describes antigenic and host factors of possible significance in the immunopathogenesis of hypersensitivity pneumonitis (HP). Although certain immunologic studies suggest immune complex mechanisms in HP, recent experimental and clinical data accumulated support a role for cell-mediated immunity. In addition, some data support roles for anaphylactic and cytotoxic antibody-mediated reactivity as well. One type of reactivity alone may not be sufficient for production of HP, and local pulmonary immune responses may be most relevant to the pathogenesis. Whether immune damage will be produced in an exposed individual or not may depend on the characteristics of the antigenic exposure as well as inherited and acquired individual differences in immunologic reactivity and possibly target organ sensitivity.