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Immunity in the respiratory tract
313
Immunology Today, vol. 6, No. 11, 1985
Immunity in the respiratory tract from Ch. Bergmann, R. Clancy and K . Petzoldt The mucosal surfaces of the gut and respiratory tract are often considered as equivalent from an immunological point of view, a tendency encouraged by the fact that far more is k n o w n about gut i m m u n i t y . But there are profound differences in the defence mechanisms at each type of surface and some of these were discussed at a recent meeting*.
The number and nature of lymphocyte subsets and accessory cells differ in the compartments of the respiratory tract, and alter from the nasal mucosa down to the bronchoalveolar space (R. Pabst, Hannover). There are also changes in the type of antibody response stimulated, the predominant local IgA response giving way to a systemic IgG response as one descends the respiratory tract (S. Ahlstedt, G6teborg). The intrapulmonary region of the respiratory tract is essentially antigen free, unlike the gut. Variations within the animal species due to breeding conditions and between species with respect to antigen contamination of the lower respiratory tract probably account for differences in the amount of bronchus-associated lymphoid tissue and the number of inflammatory cells like mast cells and goblet cells. The bronchus-associated lymphoid tissue is poorly developed in healthy people (J. Bienenstock, Hamilton). There are striking physiological differences between the gut and respiratory tract concerning antigen handling, directional flow of intermucosal traffic, and responsiveness of the mucosa to antigenic stimulation. The respiratory tract mucosa interacts with other mucosal surfaces (in addition to the systemic immune apparatus in the terminal respiratory tract as described above) in severn ways. Antigen is transported; for example, via mucociliary apparatus to the gut and,if soluble, is absorbed by alveolar macrophages. Cells migrate predominantly from the gut to the lung (but the data are incomplete) and there are IgA 'pumps', at least within the salivary and biliary systems, which selectively remove secretory IgA (and any attached antigen) from the circulation. This system may contribute to antigen handling of an inhaled soluble antigen, with subsequent presentation to the gut. The significance of the 'pumps' in man requires clarification, particularly as they appear quantitatively less effective than those found in rodents (Ahlstedt). *The t-thmeetingofthe Commissionfor Immunologyof the International Societyfor Aerosolsin Medicine, sponsored by the Stiftung Volkswagenwerk, was held in Hanover, FRG, 13-15 September 1984.
Secretory IgA and IgE An essential and unique protective role for secretory IgA(sIgA) has not been proved in developed countries. Isolated IgA deficiency is probably not associated with infection in the absence of an additional defect in host defence. Thus, the traditional concept of IgA as the essential first line of defence against a limited amount of antigen is probably incorrect (J. G. Hall, Sutton). Under normal circumstances, however, IgA antibody provides an important contribution to the defence of the upper respiratory tract. Indeed, in antigen excess, as yet uninvestigated, IgA antibody may be crucial. Previous invitro studies on IgA function have not always been precise because of contamination of the IgA antibody by antibodies of other isotypes, e.g., IgG. Preliminary studies with monoclonal IgA antibody, however, have shown a lack of traditional secondary antibody activities such as complement activation (D. L. Delacroix, Brussels). This statement does not take into consideration the IgE response to inhaled antigen or the interaction between the local immune and 'end organ' responses (such as bronchial reactivity). The general comment, however, can be made that when antigen is inhaled IgE antibody often contributes to secretions, together with other effector immune components. This broad immune response, in some individuals, can modify bronchial reactivity, so that subsequent exposure to antigen causes a biphasic bronchoconstrictor response. It remains unclear what determines the exaggerated IgE response which characterizes the atopic state (J. F. Soothill, London). Cellular i m m u n i t y Cellular immunity operates within the mucosa of the respiratory tract, as demonstrated by the appearance of activated and cytotoxic T lymphocytes following inhalation of antigen. Under such conditions natural killer cell activity and activated macrophages probably contribute to defence. The relationship between immune stimulation, and also immune regulation, and the macrophage requires better definition.
The significance in vivo of the many and varied studies on cell function in vitro needs clarification, especially with respect to the regulatory function of T-cell subsets and large granulated lymphocytes in human respiratory mucosa. The kinetics of, and relationships between, cells derived from the different 'compartments' of the respiratory tract have not been separated and such difficulties cloud interpretation of bronchoalveolar cell populations found in disease. It should be stressed that limited studies in man have often neglected the observation that circulating antibodies and pulmonary T cells may respond to inhaled antigen, so that positive tests in vitro may reflect only sensitization and not necessarily contribute to pathogenesis (A. Tagliabue, Siena). Mast cells play a crucial role in mucosal physiology and pathology. However, both the stimuli for the activation of mast cells and the processes responsible for the control of mast cell function remain poorly understood. Mast cells provide a final common path for both specific and non-specific activators. Mast cell kinetics, with respect to precursor cell relationships, levels of heterogeneity, and the fate of mast cells, require new approaches in addition to the culture and cloning techniques currently in use. Mast cells may also be the link between the immune system and the neurological system through their activation by neuropeptides like substance P which are released by noxious stimuli on the mucous membrane. Nonspecific mediators There is evidence for a major presence of nonspecific mediators of inflammation such as prostaglandins leukotrienes, interferon and lysozyme that are present in respiratory mucosa (R. Fontanges, Lyon; W. K6nig, Bochum). There is a need to study control processes such as levels of critical enzymes in mucosal tissues and levels of inhibitors (e. g. protease inhibitors) in order to understand the relevance of these pathways (B. Rasche, Bochum). Need for standardization The variable results emerging from different laboratories emphasize the importance of standardizing technology, experimental design, and subject populations in the study of the human respiratory tract. In particular, attention should be given to:
(1) Sampling procedures, e.g. collection of nasal and salivary secretions, and bronchoalveolar washings including use of appropriate correction factors, to
© 1985, El~vier Science Publi~he~ S.V.,.Anasterdart~
0167 - 4919/85/$02 00
Immunology Today, vol. 6, No. 11, 1985
314 enable correlations between different laboratories. The relationships between the different molecular and cellular populations obtained by sampling within the respiratory tract must be clearly defined with respect to source, kinetics, functions and interactions. (2) Development of international standards and criteria, e.g. a secretory I g A standard of known and stable polymer size, and criteria for characterizing lumenal cell types. (3) Diagnostic criteria of patient populations remain variable. This is particularly important with respect to the respiratory tract mucosa where age, lumenal content, experience and disease state can alter immune function and status. Local vaccines The development of local vaccines operating through a stimulation of respiratory tract immunity in man has been largely empirical. Direct presentation of live or killed virus vaccine to the respiratory tract can stimulate the antibody content of local secretions and protection. Live vaccines stimulate a more profound and durable immunity as evi-
denced by studies with influenza vaccines (H. J. Raettig, Berlin). Ingestion of killed virus and bacteria at appropriate dose levels stimulates IgA antibody levels in upper respiratory tract secretions, though protection remains to be demonstrated. Local vaccines may theoretically shift the balance of control of the local immune response so that a net suppression is induced, with a subsequent enhancement of infection. Results from normal young adults cannot necessarily be extended to older patients, or those with an abnormal respiratory tract (R. Clancy, Newcastle). Further research Animal studies are important for studying normal mechanisms, but cannot substitute for studies in man. In the analysis of the pathogenesis of human respiratory disease, experimental models have contributed little. Study of individuals provides only limited information on mucosal immune status. Epidemiological studies, however, over a period of time are useful in, for example, correlating early life events, mucosal immune function and subse-
Autoantibodies and nuclear antigens from D. I. Stott Autoantibodies against nuclear antigens are c o m m o n in the systemic rheumatic diseases. About sixteen such antigens have been characterized and they have been located in all the nuclear compartments. Little is k n o w n about the biological roles of these antigens but the significance and function of autoantibodies to them was one of the themes of a recent meeting*.
There are several reasons why a conference on this subject should attract 300 scientists from all over Europe and the USA. Detection of serum autoantibodies against certain nuclear antigens is a valuable aid to diagnosis, the most notable examples being Sm (correlating strongly with SLE) and Scl 70, an antigen found in cases of scleroderma. Levels of autoantibody against particular antigen may give an indication of the patient's prognosis and it is hoped that a detailed knowledge of the specificity of these autoantibodies and their relationship to autoimmune disease may lead to improvements in therapy. Such studies may also resuk in a better understanding of the aetiology of the autoimmune response. Finally, there is an enormous variety of proteins found in the nucleus, often associated with chromatin, and some of these are thought to be involved in the control of gene expression. Mol*The 33rd Colloquium, Protides of Biological Fluids, was held in Brussels, 29 April-1 May 1985.
ecular biologists are looking for antibodies against these proteins as probes with which to dissect the mechanisms operating in the cell nucleus. The immunoblotting technique has improved the identification and characterization of nuclear antigens and allowed a more precise definition of the specificities of autoantibodies for epitopes on the polypeptides of the particulate R N P and Sm antigens. Extensive immunoblotting studies have shown that all anti-RNP sera react with one or more of three polypeptides of Mr 70 000, 31 000 and 19 000 and all anti-Sm sera react with polypeptides of M r 25 000 and/or 13 000. The 70 000 polypeptide is associated with the U1 .-RNA particle and the M r 25 000 doublet with Sm antigen. The La (MT 50 000) and Ro (M, 60 000) antigens, found mainly in the cytoplasm and Crest 17 (a Mr 1'7 000 chromatin protein) have also been characterized by immunoblotting. Sera from scleroderma patients have specificity for a M r 19 000 centromere protein in addition to Scl-86, aM, 86 000
© 1985, Elsevier Science Publishers B.V., Amsterdam 0167 - 4919/85/$02.00
quent disease, host-parasite relationships in developed and developing countries, and in assessing local immunization strategies. Early events at a mucosal surface appear to be crucial in determining patterns of mucosal immune response and disease. Extrinsic factors such as feeding patterns, gut colonization, and socioeconomic factors require further study. Study of mucosal and intralumenal events must be examined as early key components in the development of a number of pulmonary diseases (e.g., bronchkis, pneumonia, extrinsic alveolifts), and must not be clouded by changes in systemic immunity which occur late in the disease process.
LIJ
Christian Bergmann is at the Research Institute o n Lung Diseases and Tuberculosis, Department of Clinical Immunology, Karower Strasse 11, 1115 Berlin, GDR; Robert Clancy is in the Faculty of Medicine, Royal Newcastle Hospital, Newcastle, New South Wales, Australia 2300; and Klaas Petzoldt is at the Institute ofMicrobiologyand Infictioas Diseases of the Hannover School of Veterinary Medicine, BischofsholerDatum 15, 3000 Hannover 1, FRG.
nuclear matrix protein. W. J. Habets (Nijmegen) described the quantitation of antibody specific for a single polypeptide by immunoblotting followed by elution of the bound antibody; this could prove useful in determining whether the level of a particular antibody correlates with the progress of the disease. Quantitation by scanning the fluorographs, as used in other systems, is also an approach worth pursuing in view of the dangers of incomplete elution and loss of activity during elution. Other interesting autoantibodies react with a ribosomal RNP particle (in SLE) or alanyl-tRNA synthetase and alanyltRNA (in myositis). The anti-alanyltRNA synthetase appears to react with the t R N A binding site of the enzyme and it was suggested by R. M. Bernstein (London) that the anti-tRNA, which is found in the same patients, may be an anti-idiotype for the former autoantibody, A problem when using sera from autoimmune patients to characterize nuclear antigens is that most sera are polyspecitic. However, D. G. Williams and R. N. Maini (London) described the use of monoclonal antibodies derived from M R L / l p r mice for analysis of the Sm and La antigens. Attempts to correlate autoantibodies against nuclear antigens with disease activity have not always been successful, perhaps the best example being the correlation between the titre of anti-dsDNA and glomerulonephritis. This disease
Immunology Today, vol. 6, No. 11, 1985
Immunity in the respiratory tract from Ch. Bergmann, R. Clancy and K . Petzoldt The mucosal surfaces of the gut and respiratory tract are often considered as equivalent from an immunological point of view, a tendency encouraged by the fact that far more is k n o w n about gut i m m u n i t y . But there are profound differences in the defence mechanisms at each type of surface and some of these were discussed at a recent meeting*.
The number and nature of lymphocyte subsets and accessory cells differ in the compartments of the respiratory tract, and alter from the nasal mucosa down to the bronchoalveolar space (R. Pabst, Hannover). There are also changes in the type of antibody response stimulated, the predominant local IgA response giving way to a systemic IgG response as one descends the respiratory tract (S. Ahlstedt, G6teborg). The intrapulmonary region of the respiratory tract is essentially antigen free, unlike the gut. Variations within the animal species due to breeding conditions and between species with respect to antigen contamination of the lower respiratory tract probably account for differences in the amount of bronchus-associated lymphoid tissue and the number of inflammatory cells like mast cells and goblet cells. The bronchus-associated lymphoid tissue is poorly developed in healthy people (J. Bienenstock, Hamilton). There are striking physiological differences between the gut and respiratory tract concerning antigen handling, directional flow of intermucosal traffic, and responsiveness of the mucosa to antigenic stimulation. The respiratory tract mucosa interacts with other mucosal surfaces (in addition to the systemic immune apparatus in the terminal respiratory tract as described above) in severn ways. Antigen is transported; for example, via mucociliary apparatus to the gut and,if soluble, is absorbed by alveolar macrophages. Cells migrate predominantly from the gut to the lung (but the data are incomplete) and there are IgA 'pumps', at least within the salivary and biliary systems, which selectively remove secretory IgA (and any attached antigen) from the circulation. This system may contribute to antigen handling of an inhaled soluble antigen, with subsequent presentation to the gut. The significance of the 'pumps' in man requires clarification, particularly as they appear quantitatively less effective than those found in rodents (Ahlstedt). *The t-thmeetingofthe Commissionfor Immunologyof the International Societyfor Aerosolsin Medicine, sponsored by the Stiftung Volkswagenwerk, was held in Hanover, FRG, 13-15 September 1984.
Secretory IgA and IgE An essential and unique protective role for secretory IgA(sIgA) has not been proved in developed countries. Isolated IgA deficiency is probably not associated with infection in the absence of an additional defect in host defence. Thus, the traditional concept of IgA as the essential first line of defence against a limited amount of antigen is probably incorrect (J. G. Hall, Sutton). Under normal circumstances, however, IgA antibody provides an important contribution to the defence of the upper respiratory tract. Indeed, in antigen excess, as yet uninvestigated, IgA antibody may be crucial. Previous invitro studies on IgA function have not always been precise because of contamination of the IgA antibody by antibodies of other isotypes, e.g., IgG. Preliminary studies with monoclonal IgA antibody, however, have shown a lack of traditional secondary antibody activities such as complement activation (D. L. Delacroix, Brussels). This statement does not take into consideration the IgE response to inhaled antigen or the interaction between the local immune and 'end organ' responses (such as bronchial reactivity). The general comment, however, can be made that when antigen is inhaled IgE antibody often contributes to secretions, together with other effector immune components. This broad immune response, in some individuals, can modify bronchial reactivity, so that subsequent exposure to antigen causes a biphasic bronchoconstrictor response. It remains unclear what determines the exaggerated IgE response which characterizes the atopic state (J. F. Soothill, London). Cellular i m m u n i t y Cellular immunity operates within the mucosa of the respiratory tract, as demonstrated by the appearance of activated and cytotoxic T lymphocytes following inhalation of antigen. Under such conditions natural killer cell activity and activated macrophages probably contribute to defence. The relationship between immune stimulation, and also immune regulation, and the macrophage requires better definition.
The significance in vivo of the many and varied studies on cell function in vitro needs clarification, especially with respect to the regulatory function of T-cell subsets and large granulated lymphocytes in human respiratory mucosa. The kinetics of, and relationships between, cells derived from the different 'compartments' of the respiratory tract have not been separated and such difficulties cloud interpretation of bronchoalveolar cell populations found in disease. It should be stressed that limited studies in man have often neglected the observation that circulating antibodies and pulmonary T cells may respond to inhaled antigen, so that positive tests in vitro may reflect only sensitization and not necessarily contribute to pathogenesis (A. Tagliabue, Siena). Mast cells play a crucial role in mucosal physiology and pathology. However, both the stimuli for the activation of mast cells and the processes responsible for the control of mast cell function remain poorly understood. Mast cells provide a final common path for both specific and non-specific activators. Mast cell kinetics, with respect to precursor cell relationships, levels of heterogeneity, and the fate of mast cells, require new approaches in addition to the culture and cloning techniques currently in use. Mast cells may also be the link between the immune system and the neurological system through their activation by neuropeptides like substance P which are released by noxious stimuli on the mucous membrane. Nonspecific mediators There is evidence for a major presence of nonspecific mediators of inflammation such as prostaglandins leukotrienes, interferon and lysozyme that are present in respiratory mucosa (R. Fontanges, Lyon; W. K6nig, Bochum). There is a need to study control processes such as levels of critical enzymes in mucosal tissues and levels of inhibitors (e. g. protease inhibitors) in order to understand the relevance of these pathways (B. Rasche, Bochum). Need for standardization The variable results emerging from different laboratories emphasize the importance of standardizing technology, experimental design, and subject populations in the study of the human respiratory tract. In particular, attention should be given to:
(1) Sampling procedures, e.g. collection of nasal and salivary secretions, and bronchoalveolar washings including use of appropriate correction factors, to
© 1985, El~vier Science Publi~he~ S.V.,.Anasterdart~
0167 - 4919/85/$02 00
Immunology Today, vol. 6, No. 11, 1985
314 enable correlations between different laboratories. The relationships between the different molecular and cellular populations obtained by sampling within the respiratory tract must be clearly defined with respect to source, kinetics, functions and interactions. (2) Development of international standards and criteria, e.g. a secretory I g A standard of known and stable polymer size, and criteria for characterizing lumenal cell types. (3) Diagnostic criteria of patient populations remain variable. This is particularly important with respect to the respiratory tract mucosa where age, lumenal content, experience and disease state can alter immune function and status. Local vaccines The development of local vaccines operating through a stimulation of respiratory tract immunity in man has been largely empirical. Direct presentation of live or killed virus vaccine to the respiratory tract can stimulate the antibody content of local secretions and protection. Live vaccines stimulate a more profound and durable immunity as evi-
denced by studies with influenza vaccines (H. J. Raettig, Berlin). Ingestion of killed virus and bacteria at appropriate dose levels stimulates IgA antibody levels in upper respiratory tract secretions, though protection remains to be demonstrated. Local vaccines may theoretically shift the balance of control of the local immune response so that a net suppression is induced, with a subsequent enhancement of infection. Results from normal young adults cannot necessarily be extended to older patients, or those with an abnormal respiratory tract (R. Clancy, Newcastle). Further research Animal studies are important for studying normal mechanisms, but cannot substitute for studies in man. In the analysis of the pathogenesis of human respiratory disease, experimental models have contributed little. Study of individuals provides only limited information on mucosal immune status. Epidemiological studies, however, over a period of time are useful in, for example, correlating early life events, mucosal immune function and subse-
Autoantibodies and nuclear antigens from D. I. Stott Autoantibodies against nuclear antigens are c o m m o n in the systemic rheumatic diseases. About sixteen such antigens have been characterized and they have been located in all the nuclear compartments. Little is k n o w n about the biological roles of these antigens but the significance and function of autoantibodies to them was one of the themes of a recent meeting*.
There are several reasons why a conference on this subject should attract 300 scientists from all over Europe and the USA. Detection of serum autoantibodies against certain nuclear antigens is a valuable aid to diagnosis, the most notable examples being Sm (correlating strongly with SLE) and Scl 70, an antigen found in cases of scleroderma. Levels of autoantibody against particular antigen may give an indication of the patient's prognosis and it is hoped that a detailed knowledge of the specificity of these autoantibodies and their relationship to autoimmune disease may lead to improvements in therapy. Such studies may also resuk in a better understanding of the aetiology of the autoimmune response. Finally, there is an enormous variety of proteins found in the nucleus, often associated with chromatin, and some of these are thought to be involved in the control of gene expression. Mol*The 33rd Colloquium, Protides of Biological Fluids, was held in Brussels, 29 April-1 May 1985.
ecular biologists are looking for antibodies against these proteins as probes with which to dissect the mechanisms operating in the cell nucleus. The immunoblotting technique has improved the identification and characterization of nuclear antigens and allowed a more precise definition of the specificities of autoantibodies for epitopes on the polypeptides of the particulate R N P and Sm antigens. Extensive immunoblotting studies have shown that all anti-RNP sera react with one or more of three polypeptides of Mr 70 000, 31 000 and 19 000 and all anti-Sm sera react with polypeptides of M r 25 000 and/or 13 000. The 70 000 polypeptide is associated with the U1 .-RNA particle and the M r 25 000 doublet with Sm antigen. The La (MT 50 000) and Ro (M, 60 000) antigens, found mainly in the cytoplasm and Crest 17 (a Mr 1'7 000 chromatin protein) have also been characterized by immunoblotting. Sera from scleroderma patients have specificity for a M r 19 000 centromere protein in addition to Scl-86, aM, 86 000
© 1985, Elsevier Science Publishers B.V., Amsterdam 0167 - 4919/85/$02.00
quent disease, host-parasite relationships in developed and developing countries, and in assessing local immunization strategies. Early events at a mucosal surface appear to be crucial in determining patterns of mucosal immune response and disease. Extrinsic factors such as feeding patterns, gut colonization, and socioeconomic factors require further study. Study of mucosal and intralumenal events must be examined as early key components in the development of a number of pulmonary diseases (e.g., bronchkis, pneumonia, extrinsic alveolifts), and must not be clouded by changes in systemic immunity which occur late in the disease process.
LIJ
Christian Bergmann is at the Research Institute o n Lung Diseases and Tuberculosis, Department of Clinical Immunology, Karower Strasse 11, 1115 Berlin, GDR; Robert Clancy is in the Faculty of Medicine, Royal Newcastle Hospital, Newcastle, New South Wales, Australia 2300; and Klaas Petzoldt is at the Institute ofMicrobiologyand Infictioas Diseases of the Hannover School of Veterinary Medicine, BischofsholerDatum 15, 3000 Hannover 1, FRG.
nuclear matrix protein. W. J. Habets (Nijmegen) described the quantitation of antibody specific for a single polypeptide by immunoblotting followed by elution of the bound antibody; this could prove useful in determining whether the level of a particular antibody correlates with the progress of the disease. Quantitation by scanning the fluorographs, as used in other systems, is also an approach worth pursuing in view of the dangers of incomplete elution and loss of activity during elution. Other interesting autoantibodies react with a ribosomal RNP particle (in SLE) or alanyl-tRNA synthetase and alanyltRNA (in myositis). The anti-alanyltRNA synthetase appears to react with the t R N A binding site of the enzyme and it was suggested by R. M. Bernstein (London) that the anti-tRNA, which is found in the same patients, may be an anti-idiotype for the former autoantibody, A problem when using sera from autoimmune patients to characterize nuclear antigens is that most sera are polyspecitic. However, D. G. Williams and R. N. Maini (London) described the use of monoclonal antibodies derived from M R L / l p r mice for analysis of the Sm and La antigens. Attempts to correlate autoantibodies against nuclear antigens with disease activity have not always been successful, perhaps the best example being the correlation between the titre of anti-dsDNA and glomerulonephritis. This disease