Path. Res. Pract. 186,687-691 (1990)
Pulmonary Corpora Amylacea Contain Surfactant Apoprotein 1: Akino, M. Mizumoto, H. Shimizu, Y. Kuroki and K. Dempo Departments of Biochemistry and Pathology, Sapporo Medical College, Sapporo, Japan
T. Tsuda, S. Yanai and M. Mizuki Department of Medicine, Oita Medical College, Hazama-Cho, Oita-Gun, Oita-Ken, Japan
SUMMARY The case of a 53-year-old female with interstitial pneumonitis is described with special regard to biochemical characterization ofpulmonary corpora amylacea which were found in the lung specimen obtained by bronchial biopsy from the patient. The main protein component in bronchoalveolar lavage (BAL) fluid ofthe patient was albumin, but proteins in the precipitate fraction of BAL fluid, where the corpora amylacea were recovered, predominantly consisted of 36 kD protein which was stained with the monoclonal antibody PE 10 to human pulmonary surfactant apoprotein by immunoblot. Histologically the pulmonary corpora amylacea were stained with eosin and PAS. The particles were stained immunohistochemically by immunoperoxidase reaction using PE 10, but not by antibodies to human albumin. The pulmonary surfactant apoprotein seems, therefore, to be not simply adsorbed in the particles, but to be contained in them. Thus, the surfactant apoprotein may, at least in this case, be involved in the formation of pulmonary corpora amylacea.
Case Report A 53-year-old woman was admitted to the First Department of Medicine, Medical College Hospital of Oita on September 30th, 1985, because of dry cough and exertional dyspnea. She had been susceptible to a cold since her childhood. For the last 3 years she had noticed a persistent dry cough and mild exertional dyspnea which had become severer since July 1985, so she called on her family doctor on September 6th and had a chest X-ray film which showed abnormal findings. She was born in an immature condition, and she began to walk at the age of three. She had never smoked. She had been a hospitalkeeper for 12 years, so there was a history of exposure to dust. On admission her vital signs were almost normal. On chest examination fine crackles were heard on both © 1990 by Gustav Fischer Verlag, Stuttgart
posterior bases. Chest X-ray film revealed fine diffuse reticular shadows in both lower lung fields, predominantly in the right lower lobe. The hemogram was normal and blood biochemical findings were almost normal except for slightly increased LDH. In immunological findings, RA test was 2 plus, and IgA, M, and G were normal but IgE was high (1169 !t/ml). Blood gas analysis revealed slightly decreased pOz level (70 Torr), and Aa-DO z was wide. Pulmonary function test showed a moderate constrictive pattern (% CV was 68.9%) and decreased DLCO (%DLCO was 63.2%). Lung specimen from the right lower lobe (rSe) was taken by transbronchial biopsy and subjected to light microscopy and immunohistochemical studies. Bronchoalveolar lavage (BAL) fluid was obtained from the right lower lobe through bronchofiberscope. Blood gas 0344·0338/9010186·0687$3.5010
688 . Akino, T. et al.
findings were improved slightly after the partial BAL procedure. On February 7th, we lavaged her right lung with total 8430 ml of saline according to the method described by Ramirez et al. 8 under general anesthesis. After the lung lavage the shadow of the right lower field was decreased slightly and the pOz level was improved to 85-90 Torr. Exertional dyspnea was also improved, but vital capacity and DLCO were not improved sufficiently yet. She was discharged on March 2nd, 1986 and now she is almost fine, taking 15 mg of predonisolone every morning for the purpose of treatment for interstitial pneumonitis. Histology A considerable thickening of interalveolar septa and homogenous round bodies with sizes from 50 to 80 ~ in
Fig. 2. PAS staining of the lung section. Positive PAS reaction in the round bodies (x 160).
Fig. 1. Hematoxylin-eosin staining of the lung section. Aconsiderable thickening of interalveolar septa and homogenous round bodies with sizes from 50 to 80 !! in diameter in the alveolar spaces (x 160) is observed.
diameter were observed in the alveolar spaces. The round bodies were laminated and frequently surrounded by alveolar macrophages. They stained pink with hematoxylin and eosin (Fig. 1) and stained positive for PAS reaction (Fig. 2). But they stained negative with both Alcian blue and Sudan III. So these round bodies were determined as pulmonary corpora amylacea associated with interstitial pneumonitis. Immunohistological staining with a monoclonal antibody PE 10 to human pulmonary surfactant 36 kD apoprotein 3,4 revealed that the round bodies, i.e., pulmonary corpora amylacea, were distinctly positive (Fig. 3). The staining was homogenous in the round bodies. The intense stainings were also observed on the walls and inside the alveoli (Fig. 4). The corpora amylacea particles were not stained immunohistochemicallY by anti-human albumin antibodies. These findings indicate that pulmonary surfactant 36 kD apoprotein is not simply adsorbed to the corpora amylacea, but is contained in them.
Pulmonary Corpora Amylacea . 689
Fig. 3. Immunoperoxidase stammgs for PE 10 are distinctly observed in the round bodies of the lung section (x 170).
Protein Analysis The bronchoalveolar lavage (BAL) fluid of the patient was centrifuged at 500 xg for 10 min 7 . The rounded bodies were recovered in the BAL precipitate. The supernatant and precipitate fractions were subjected to protein analysis by sodium dodecylsulfate polyacrylamide gel electrophoresiss . The supernatant fraction contained albumin as the main component, while 36 kD protein was a predominant protein component in the precipitate fraction (Fig. 5). Furthermore, this 36 kD protein band was definitely stained by immunoperoxidase reaction using PE 10. The 62 kD and 28 kD proteins were also stained by this immunoblot. The former has been shown to be a dimer of 36 kD protein9 and the latter to be a primary translation product in humans ll . The particles might be comprised only as a part of the BAL precipitate. However, data on the protein analysis indicate that the BAL precipitate contains no other protein components than surfactant apoprotein.
Fig. 4. Immunoperoxidase stainings for PE 10 are also observed in the wall and inside the alveoli of the lung section (x 142).
Discussion The term pulmonary corpora amylacea is applied to rounded, eosin staining, acellular structures found in the alveoli of lungs removed postmortem, and in septum before death 1o . Despite morphologicaF,6 and biochemicaP studies the pathogenesis of these curious structures has not been clarified. Barr and Ferguson 1 studied the biochemical composition and concluded that glycoproteins were the principal constituents. We found pulmonary corpora amylacea histologically in the lung specimen taken by transbronchial biopsy from a patient with interstitial pneumonitis. This is a first report to suggest that pulmonary surfactant 36 kD apoprotein, i.e., a glycoprotein occurring to a great extent in the alveoli, is involved in the formation of pulmonary corpora amylacea. The prominent protein in BAL-precipitate fraction in this case was 36 kD protein. This protein was identified to be a surfactant apoprotein, since it reacted with the monoclonal antibody to pulmonary surfactant 36 kD
690 . Akino, T. et al.
apoprotein. Although the particles were recovered in the BAL precipitate, they might consist only partly in the BAL precipitate. Therefore, there seemingly is no direct link between the BAL precipitate and the particles seen histologically. However, the pulmonary corpora amylacea observed in lung specimen of this case were immunohistochemically stained by immunoperoxidase reaction with the monoclonal antibody. It is possible that the immunostaining of the particles may be simply due to nonspecific adhesion of the surfactant components to the corpora amylacea. If the immunostaining by the monoclonal antibody shows, indeed, nonspecific adhesion of the surfactant apoprotein, other components present in the alveoli should also be adsorbed to the corpora amylacea. However, the particles were not stained immunohistochemically by antibodies to human albumin which was a main protein component in the alveoli of this case. Therefore, the immunostaining observed in the corpora amylacea with a monoclonal antibody to 36 kD apoprotein seems to be specific for the particles. These findings demonstrate that pulmonary surfactant 36 kD apoprotein is contained in the pulmonary corpora amylacea. Barr and Ferguson! reported that glycoproteins are principal constituents of the pulmonary corpora amylacea. The glycoproteins, which they pointed out, seem to be pulmonary surfactant 36 kD apoprotein. The cause of corpora amylacea in the lung is unknown. Hollander and Hutchins2 described the special importance of central particles for the formation of corpora amylacea, and that the particulate foreign material might act as a
A· 1
2
3 4
nidus or nucleation center for the formation. They suggest that the spheres are derived from plant spores and a possible origin is from inspired lycopodium spores, which are used as a dusty powder. Combining this suggestion and our present results, the following hypothesis is presented for formation of pulmonary corpora amylacea, at least in this case: the nuclei of the corpora amylacea may be initially formed with some dusts, and then the components of pulmonary surfactant accumulate surrounding the nuclei to form the lamellar structure, i.e., pulmonary corpora amylacea. Acknowledgement This study was supported in part by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture, Japan.
References 1 Barr HS, Ferguson FF (1963) Microlithiasis alveolaris pulmonum: Association with diffuse interstitial pulmonary fibrosis. Arch Pathol 76: 659-666 2 Hollander DH, Hutchins GM (1978) Central spherules in pulmonary corpora amylacea. Arch Pathol Lab Med 102: 629-630 3 Kuroki Y, Fukada Y, Takahashi H, Akino T (1985) Monoclonal antibodies against human pulmonary surfactant apoproteins: specificity and application in immunoassay. Biochim Biophys Acta 836: 201-209
B
5
3
4
5
a b
.....62K
c d
e f
...36K
...36K
Fig. 5. SDS-polyacrylamide gel electrophoresis and immunoblotting of the proteins contained in bronchoalveolar lavage (BAL) fluid. - A: The gel was stained with amidoblack. B: Western blotting of A. The proteins on the gel were transferred to nitrocellulose sheet and stained with PE 10. - 1: standard proteins. a: phosphorylase b (M.W., 89000), b: albumin (M.W., 63000), c: ovalbumin (M.W., 40500), d: carbonic anhydrase (M.W., 28300), e: trypsin inhibitor (M.W., 18800), f: a-lactoalbumin (M.W., 13 600). - 2: human serum (protein 10 [.tg). - 3: pulmonary surfactant apoproteins from BAL fluid of patients with alveolar proteinosis (protein 15 [.tg). - 4: supernatant fraction of patient's BAL fluid (protein 132 [.tg). - 5: precipitate fraction of patient's BAL fluid (protein 15 [.tg).
Pulmonary Corpora Amylacea . 691 4 Kuroki Y, Dempo K, Akino T (1986) Immunohistochemical study of human pulmonary surfactant apoproteins with monoclonal antibodies. Pathological application for hyaline membrane disease. Am J Pathol124: 25-33 5 Laemmli UK (1970) Cleavage of structural proteins during assembly of the head of bacteriophage T 4. Nature 227: 680-685 6 Michaels L, Levine C (1957) Pulmonary corpora amylacea. J Pathol Bacteriol 74: 49-56 7 Onodera T, Nakamura M, Sato T, Akino T (1983) Biochemical characterization of pulmonary washings of patients with alveolar proteinosis, interstitial pneumonitis and alveolar carcinoma. Tohoku J Exp Med 139: 245-263
8 Ramirez-R J, Schultz RB, Dutton RE (1963) Pulmonary alveolar proteinosis. Anew technique and rationale for treatment. Arch Int Med 112: 419-431 9 Ross GF, Ohning BL, Tannenbaum D, Whitsett JA (1987) Structural relationships of the major glycoproteins from human alveolar proteinosis surfactant. Biochim Biophys Acta 911: 294-304 10 Spencer H (1985) Pathology of the Lung. Pergamon Press, Oxford-New York-Toronto. Vol. 2: p 680-681 11 White RT, Damm D, Miller J, Spratt K, Schilling J, Hawgood S, Benson B, Cordell B(1985) Isolation and characterization of the human pulmonary surfactant apoprotein gene. Nature 317: 361-363
Received March 2, 1989 . Accepted in revised form February 15, 1990
Key words: Pulmonary corpora amylacea - Pulmonary surfactant - Interstitial pneumonitis - Pulmonary surfactant apoprotein Toyoaki Akino, Department of Biochemistry, Sapporo Medical College, South-I, West-I?, Chuo-Ku, Sapporo 060, Japan
Letters to the Case
s. L. Katyal
Pittsburgh, USA The case report by Akino et al. shows the presence of surfactant apoprotein A (SP-A) in corpora amylacea rich precipitate recovered from bronchoalveolar lavage (BAL) of a patient with interstitial pneumonitis. The particles were stained by the immunoperoxidase staining using a monoclonal antibody (PE 10) to SP-A. However, no staining was observed when an antibody to human albumin was used in the same staining procedure. This observation is important in view of the high concentrations of albumin in BAL of the patient and, therefore, indicates that SP-A is at least one of components involved in the formation of corpora amylacea. SP-A is associated with disaturated phosphatidylcholine (the major surface-active component of pulmonary surfactant), other lipids and proteins, SP-B and SP-Cl,3. Further analysis of corpora amylacea particles is important in order to determine whether other surfactant components are also involved in the formation of the particles. It would also be interesting to determine whether SP-A found in corpora amylacea is structurally different from the SP-A found in normal human lungs. Structural alterations could involve the carbohydrate moiety and aggregation of the protein chains. SP-A is a sialo-glycoprotein and shows charge and
molecular heterogeneities2,5. Human SP-A consists of a collagen-like domain of 72 amino acids and a globular domain 6 • Both interchain and intrachain disulfide bonds lead to the formation of oligomers of SP-A2,5. SP-A appears to form structures resembling six flowers with stalks joined together, as has been shown by electronmicroscopy using rotary shadowing technique4. Such structures of SP-A consist of six globular domains and a collagen-like triple helix4 . SP-A also accumulates in the lungs of alveolar proteinosis patients and can be recovered in large quantities from the bronchoalveolar lavage of these patients (Fig. 5). Further studies are required to demonstrate the structure SP-A as it exists in corpora amylacea. Akino et al. have presented an excellent study, which utilizes immunochemical techniques to demonstrate that at least one pulmonary surfactant component, SP-A, is present in pulmonary corpora amylacea. Further studies are required to demonstrate the structure of SP-A as it exists in corpora amylacea, and to determine whether other surfactant components are involved in the formation of these particles.
Pulmonary Corpora Amylacea Contain Surfactant Apoprotein 1: Akino, M. Mizumoto, H. Shimizu, Y. Kuroki and K. Dempo Departments of Biochemistry and Pathology, Sapporo Medical College, Sapporo, Japan
T. Tsuda, S. Yanai and M. Mizuki Department of Medicine, Oita Medical College, Hazama-Cho, Oita-Gun, Oita-Ken, Japan
SUMMARY The case of a 53-year-old female with interstitial pneumonitis is described with special regard to biochemical characterization ofpulmonary corpora amylacea which were found in the lung specimen obtained by bronchial biopsy from the patient. The main protein component in bronchoalveolar lavage (BAL) fluid ofthe patient was albumin, but proteins in the precipitate fraction of BAL fluid, where the corpora amylacea were recovered, predominantly consisted of 36 kD protein which was stained with the monoclonal antibody PE 10 to human pulmonary surfactant apoprotein by immunoblot. Histologically the pulmonary corpora amylacea were stained with eosin and PAS. The particles were stained immunohistochemically by immunoperoxidase reaction using PE 10, but not by antibodies to human albumin. The pulmonary surfactant apoprotein seems, therefore, to be not simply adsorbed in the particles, but to be contained in them. Thus, the surfactant apoprotein may, at least in this case, be involved in the formation of pulmonary corpora amylacea.
Case Report A 53-year-old woman was admitted to the First Department of Medicine, Medical College Hospital of Oita on September 30th, 1985, because of dry cough and exertional dyspnea. She had been susceptible to a cold since her childhood. For the last 3 years she had noticed a persistent dry cough and mild exertional dyspnea which had become severer since July 1985, so she called on her family doctor on September 6th and had a chest X-ray film which showed abnormal findings. She was born in an immature condition, and she began to walk at the age of three. She had never smoked. She had been a hospitalkeeper for 12 years, so there was a history of exposure to dust. On admission her vital signs were almost normal. On chest examination fine crackles were heard on both © 1990 by Gustav Fischer Verlag, Stuttgart
posterior bases. Chest X-ray film revealed fine diffuse reticular shadows in both lower lung fields, predominantly in the right lower lobe. The hemogram was normal and blood biochemical findings were almost normal except for slightly increased LDH. In immunological findings, RA test was 2 plus, and IgA, M, and G were normal but IgE was high (1169 !t/ml). Blood gas analysis revealed slightly decreased pOz level (70 Torr), and Aa-DO z was wide. Pulmonary function test showed a moderate constrictive pattern (% CV was 68.9%) and decreased DLCO (%DLCO was 63.2%). Lung specimen from the right lower lobe (rSe) was taken by transbronchial biopsy and subjected to light microscopy and immunohistochemical studies. Bronchoalveolar lavage (BAL) fluid was obtained from the right lower lobe through bronchofiberscope. Blood gas 0344·0338/9010186·0687$3.5010
688 . Akino, T. et al.
findings were improved slightly after the partial BAL procedure. On February 7th, we lavaged her right lung with total 8430 ml of saline according to the method described by Ramirez et al. 8 under general anesthesis. After the lung lavage the shadow of the right lower field was decreased slightly and the pOz level was improved to 85-90 Torr. Exertional dyspnea was also improved, but vital capacity and DLCO were not improved sufficiently yet. She was discharged on March 2nd, 1986 and now she is almost fine, taking 15 mg of predonisolone every morning for the purpose of treatment for interstitial pneumonitis. Histology A considerable thickening of interalveolar septa and homogenous round bodies with sizes from 50 to 80 ~ in
Fig. 2. PAS staining of the lung section. Positive PAS reaction in the round bodies (x 160).
Fig. 1. Hematoxylin-eosin staining of the lung section. Aconsiderable thickening of interalveolar septa and homogenous round bodies with sizes from 50 to 80 !! in diameter in the alveolar spaces (x 160) is observed.
diameter were observed in the alveolar spaces. The round bodies were laminated and frequently surrounded by alveolar macrophages. They stained pink with hematoxylin and eosin (Fig. 1) and stained positive for PAS reaction (Fig. 2). But they stained negative with both Alcian blue and Sudan III. So these round bodies were determined as pulmonary corpora amylacea associated with interstitial pneumonitis. Immunohistological staining with a monoclonal antibody PE 10 to human pulmonary surfactant 36 kD apoprotein 3,4 revealed that the round bodies, i.e., pulmonary corpora amylacea, were distinctly positive (Fig. 3). The staining was homogenous in the round bodies. The intense stainings were also observed on the walls and inside the alveoli (Fig. 4). The corpora amylacea particles were not stained immunohistochemicallY by anti-human albumin antibodies. These findings indicate that pulmonary surfactant 36 kD apoprotein is not simply adsorbed to the corpora amylacea, but is contained in them.
Pulmonary Corpora Amylacea . 689
Fig. 3. Immunoperoxidase stammgs for PE 10 are distinctly observed in the round bodies of the lung section (x 170).
Protein Analysis The bronchoalveolar lavage (BAL) fluid of the patient was centrifuged at 500 xg for 10 min 7 . The rounded bodies were recovered in the BAL precipitate. The supernatant and precipitate fractions were subjected to protein analysis by sodium dodecylsulfate polyacrylamide gel electrophoresiss . The supernatant fraction contained albumin as the main component, while 36 kD protein was a predominant protein component in the precipitate fraction (Fig. 5). Furthermore, this 36 kD protein band was definitely stained by immunoperoxidase reaction using PE 10. The 62 kD and 28 kD proteins were also stained by this immunoblot. The former has been shown to be a dimer of 36 kD protein9 and the latter to be a primary translation product in humans ll . The particles might be comprised only as a part of the BAL precipitate. However, data on the protein analysis indicate that the BAL precipitate contains no other protein components than surfactant apoprotein.
Fig. 4. Immunoperoxidase stainings for PE 10 are also observed in the wall and inside the alveoli of the lung section (x 142).
Discussion The term pulmonary corpora amylacea is applied to rounded, eosin staining, acellular structures found in the alveoli of lungs removed postmortem, and in septum before death 1o . Despite morphologicaF,6 and biochemicaP studies the pathogenesis of these curious structures has not been clarified. Barr and Ferguson 1 studied the biochemical composition and concluded that glycoproteins were the principal constituents. We found pulmonary corpora amylacea histologically in the lung specimen taken by transbronchial biopsy from a patient with interstitial pneumonitis. This is a first report to suggest that pulmonary surfactant 36 kD apoprotein, i.e., a glycoprotein occurring to a great extent in the alveoli, is involved in the formation of pulmonary corpora amylacea. The prominent protein in BAL-precipitate fraction in this case was 36 kD protein. This protein was identified to be a surfactant apoprotein, since it reacted with the monoclonal antibody to pulmonary surfactant 36 kD
690 . Akino, T. et al.
apoprotein. Although the particles were recovered in the BAL precipitate, they might consist only partly in the BAL precipitate. Therefore, there seemingly is no direct link between the BAL precipitate and the particles seen histologically. However, the pulmonary corpora amylacea observed in lung specimen of this case were immunohistochemically stained by immunoperoxidase reaction with the monoclonal antibody. It is possible that the immunostaining of the particles may be simply due to nonspecific adhesion of the surfactant components to the corpora amylacea. If the immunostaining by the monoclonal antibody shows, indeed, nonspecific adhesion of the surfactant apoprotein, other components present in the alveoli should also be adsorbed to the corpora amylacea. However, the particles were not stained immunohistochemically by antibodies to human albumin which was a main protein component in the alveoli of this case. Therefore, the immunostaining observed in the corpora amylacea with a monoclonal antibody to 36 kD apoprotein seems to be specific for the particles. These findings demonstrate that pulmonary surfactant 36 kD apoprotein is contained in the pulmonary corpora amylacea. Barr and Ferguson! reported that glycoproteins are principal constituents of the pulmonary corpora amylacea. The glycoproteins, which they pointed out, seem to be pulmonary surfactant 36 kD apoprotein. The cause of corpora amylacea in the lung is unknown. Hollander and Hutchins2 described the special importance of central particles for the formation of corpora amylacea, and that the particulate foreign material might act as a
A· 1
2
3 4
nidus or nucleation center for the formation. They suggest that the spheres are derived from plant spores and a possible origin is from inspired lycopodium spores, which are used as a dusty powder. Combining this suggestion and our present results, the following hypothesis is presented for formation of pulmonary corpora amylacea, at least in this case: the nuclei of the corpora amylacea may be initially formed with some dusts, and then the components of pulmonary surfactant accumulate surrounding the nuclei to form the lamellar structure, i.e., pulmonary corpora amylacea. Acknowledgement This study was supported in part by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture, Japan.
References 1 Barr HS, Ferguson FF (1963) Microlithiasis alveolaris pulmonum: Association with diffuse interstitial pulmonary fibrosis. Arch Pathol 76: 659-666 2 Hollander DH, Hutchins GM (1978) Central spherules in pulmonary corpora amylacea. Arch Pathol Lab Med 102: 629-630 3 Kuroki Y, Fukada Y, Takahashi H, Akino T (1985) Monoclonal antibodies against human pulmonary surfactant apoproteins: specificity and application in immunoassay. Biochim Biophys Acta 836: 201-209
B
5
3
4
5
a b
.....62K
c d
e f
...36K
...36K
Fig. 5. SDS-polyacrylamide gel electrophoresis and immunoblotting of the proteins contained in bronchoalveolar lavage (BAL) fluid. - A: The gel was stained with amidoblack. B: Western blotting of A. The proteins on the gel were transferred to nitrocellulose sheet and stained with PE 10. - 1: standard proteins. a: phosphorylase b (M.W., 89000), b: albumin (M.W., 63000), c: ovalbumin (M.W., 40500), d: carbonic anhydrase (M.W., 28300), e: trypsin inhibitor (M.W., 18800), f: a-lactoalbumin (M.W., 13 600). - 2: human serum (protein 10 [.tg). - 3: pulmonary surfactant apoproteins from BAL fluid of patients with alveolar proteinosis (protein 15 [.tg). - 4: supernatant fraction of patient's BAL fluid (protein 132 [.tg). - 5: precipitate fraction of patient's BAL fluid (protein 15 [.tg).
Pulmonary Corpora Amylacea . 691 4 Kuroki Y, Dempo K, Akino T (1986) Immunohistochemical study of human pulmonary surfactant apoproteins with monoclonal antibodies. Pathological application for hyaline membrane disease. Am J Pathol124: 25-33 5 Laemmli UK (1970) Cleavage of structural proteins during assembly of the head of bacteriophage T 4. Nature 227: 680-685 6 Michaels L, Levine C (1957) Pulmonary corpora amylacea. J Pathol Bacteriol 74: 49-56 7 Onodera T, Nakamura M, Sato T, Akino T (1983) Biochemical characterization of pulmonary washings of patients with alveolar proteinosis, interstitial pneumonitis and alveolar carcinoma. Tohoku J Exp Med 139: 245-263
8 Ramirez-R J, Schultz RB, Dutton RE (1963) Pulmonary alveolar proteinosis. Anew technique and rationale for treatment. Arch Int Med 112: 419-431 9 Ross GF, Ohning BL, Tannenbaum D, Whitsett JA (1987) Structural relationships of the major glycoproteins from human alveolar proteinosis surfactant. Biochim Biophys Acta 911: 294-304 10 Spencer H (1985) Pathology of the Lung. Pergamon Press, Oxford-New York-Toronto. Vol. 2: p 680-681 11 White RT, Damm D, Miller J, Spratt K, Schilling J, Hawgood S, Benson B, Cordell B(1985) Isolation and characterization of the human pulmonary surfactant apoprotein gene. Nature 317: 361-363
Received March 2, 1989 . Accepted in revised form February 15, 1990
Key words: Pulmonary corpora amylacea - Pulmonary surfactant - Interstitial pneumonitis - Pulmonary surfactant apoprotein Toyoaki Akino, Department of Biochemistry, Sapporo Medical College, South-I, West-I?, Chuo-Ku, Sapporo 060, Japan
Letters to the Case
s. L. Katyal
Pittsburgh, USA The case report by Akino et al. shows the presence of surfactant apoprotein A (SP-A) in corpora amylacea rich precipitate recovered from bronchoalveolar lavage (BAL) of a patient with interstitial pneumonitis. The particles were stained by the immunoperoxidase staining using a monoclonal antibody (PE 10) to SP-A. However, no staining was observed when an antibody to human albumin was used in the same staining procedure. This observation is important in view of the high concentrations of albumin in BAL of the patient and, therefore, indicates that SP-A is at least one of components involved in the formation of corpora amylacea. SP-A is associated with disaturated phosphatidylcholine (the major surface-active component of pulmonary surfactant), other lipids and proteins, SP-B and SP-Cl,3. Further analysis of corpora amylacea particles is important in order to determine whether other surfactant components are also involved in the formation of the particles. It would also be interesting to determine whether SP-A found in corpora amylacea is structurally different from the SP-A found in normal human lungs. Structural alterations could involve the carbohydrate moiety and aggregation of the protein chains. SP-A is a sialo-glycoprotein and shows charge and
molecular heterogeneities2,5. Human SP-A consists of a collagen-like domain of 72 amino acids and a globular domain 6 • Both interchain and intrachain disulfide bonds lead to the formation of oligomers of SP-A2,5. SP-A appears to form structures resembling six flowers with stalks joined together, as has been shown by electronmicroscopy using rotary shadowing technique4. Such structures of SP-A consist of six globular domains and a collagen-like triple helix4 . SP-A also accumulates in the lungs of alveolar proteinosis patients and can be recovered in large quantities from the bronchoalveolar lavage of these patients (Fig. 5). Further studies are required to demonstrate the structure SP-A as it exists in corpora amylacea. Akino et al. have presented an excellent study, which utilizes immunochemical techniques to demonstrate that at least one pulmonary surfactant component, SP-A, is present in pulmonary corpora amylacea. Further studies are required to demonstrate the structure of SP-A as it exists in corpora amylacea, and to determine whether other surfactant components are involved in the formation of these particles.
