Chest
Volume 83, Issue 1, January 1983, Pages 82-86
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Clinical Investigations
Pulmonary Alveolar Proteinosis: Staining for Surfactant Apoprotein in Alveolar Proteinosis and in Conditions Simulating It

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Formalin fixed paraffin-embedded lung tissues (n = 13) or lavage material (n = 4) from 17 patients in whom alveolar proteinosis was the primary disease and ten patients with other primary diagnoses but lung morphology similar to alveolar proteinosis were examined. The tissues were stained by the periodic acid-Schiff method and by the immunoperoxidase method for surfactant specific apoprotein. The intra-alveolar material in patients with primary alveolar proteinosis stained uniformly for surfactant specific apoprotein, whereas the staining was focal in patients with other primary diseases associated with intra-alveolar accumulation of proteinacious material. In both situations, the number of inflammatory cells, especially macrophages, was small. These observations extend an earlier impression about the presence of surfactant specific apoprotein in alveolar spaces in patients with primary alveolar proteinosis and provide a distinction between primary alveolar proteinosis and morphologically similar appearance due to other causes, ie, secondary alveolar proteinosis. The lack of macrophages in the affected tissue appears to be the major pathogenetic factor in alveolar proteinosis.

Section snippets

Materials and Methods

Formalin fixed paraffin-embedded tissue sections from patients with proven alveolar proteinosis were studied in 13 cases. Sections from blocks of lavage material were examined in another four patients. The diagnosis in all of these 17 patients had been established by open lung biopsy specimen, and the patients were successfully treated by pulmonary lavage. Tissues from five patients with intra-alveolar accumulation of PAS positive material, recognized at autopsy, associated with hematologic

Primary Alveolar Proteinosis

The intra-alveolar material stained uniformly with rabbit anti-monkey surfactant apoprotein specific IgG (SSIgG) (Fig 1). In areas where the apoprotein material was completely filling the alveoli, the staining was usually uniform; the unstained parts usually consisted of blank spaces left due to crystals, presumably cholesterol or lipid droplets. When a sizable fragment of the tissue was available, it was apparent that the accumulation of alveolar proteinosis material was not uniform.

Discussion

The two main points to be discussed in the present study are the following: (a) diagnostic specificity of PAS staining and of immunoperoxidase staining for surfactant apoprotein, to differentiate between primary and secondary pulmonary alveolar proteinosis; and (b) the information about the pathogenesis of the disease.

Staining by the PAS Method vs Immunoperoxidase Staining for Surfactant Apoprotein

Strong granular staining by the PAS method has been considered to be diagnostic of the disease even though PAS positivity is not specific for the alveolar contents of pulmonary alveolar proteinosis. It has been shown that the alveolar contents in pulmonary alveolar proteinosis are, in part, sufactant or surfactant derived.4, 5, 6, 7, 8, 9, 10, 11, 12 Thus, a specific staining method for surfactant should provide a more specific diagnostic test. This logical assumption appears to be borne out by

Pathogenesis

Surfactant, under physiologic conditions, appears to be cleared by (a) re-uptake by alveolar cells; (b) centripetal movement and along the mucociliary escalator; (c) lymphatics; and (d) macrophages.8, 15, 16, 17, 18, 19 In theory, excessive accumulation of surfactant could occur either due to excessive production or deficient removal or both.20 Earlier studies indicate that the rate of synthesis of surfactant in patients with alveolar proteinosis is not increased.21 Even though hypertrophy and

Acknowledgments

The authors are grateful to Carole Mallick for technical assistance, Linda Shab for photography, and Carolyn Karpa for typing the manuscript. The authors are also thankful to the following for their kind cooperation in providing some of the tissue blocks used in this study: Charles Kuhn, MD; Jacqueline J. Coalson, PhD; Raymond Maguire, MD; SJC Miller, MD; EG McKee, MD; Donald J Jarzynski, MD; RS Golembiewski, MD; Stanley Weitzner, MD; Alfred M. Shideler, MD; Steven C. Bauserman, MD; Harold E.

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    Manuscript received June 7; revision accepted July 30

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