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Lectin binding sites and immunocytochemical characterization of normal pleural mesothelium
C S Kortsik1, N Freudenberg, U Riede
1Department of Pneumology, University of Freiburg, Germany.
Insights
Investigating pleural mesothelium with lectins and antibodies revealed specific binding sites. Non-reactive cells with certain markers, like HPA and CEA, can confidently identify mesothelial origin in pleural effusions.
Area of Science:
- Cytopathology
- Histology
- Immunohistochemistry
Background:
- Pleural mesothelium identification is crucial for diagnosing effusions.
- Distinguishing mesothelial cells from adenocarcinoma cells can be challenging.
- Utilizing specific markers can improve diagnostic accuracy.
Purpose of the Study:
- To characterize normal pleural mesothelium using lectins and monoclonal antibodies.
- To evaluate the utility of different fixation and preparation techniques.
- To identify reliable markers for distinguishing mesothelial cells from malignant cells.
Main Methods:
- Investigated 20 normal pleural mesothelium specimens using six lectins and ten monoclonal antibodies (MAbs).
- Employed isolated cells, tissue specimens, and cytologic preparations with glutaraldehyde and formaldehyde fixation.
- Analyzed lectin binding sites and MAb reactivity, including blood group antigens Lewis(y), Lewis(b), Lewis(a), and Lewis(x).
Main Results:
- ConA, WGA, and PNA lectin binding sites were universally present; HPA, SBA, and UEA-I were absent.
- Glutaraldehyde and formaldehyde fixation yielded comparable results, allowing direct comparison of histologic and cytologic studies.
- Mesothelial cells expressed ICAM1 and pancytokeratin, but not EMA, CEA, CD24, CD15, CD20, CD5, or HEA125.
- Positive staining for Lewis(y) and Lewis(b) was observed in some specimens, while Lewis(a) and Lewis(x) were negative.
Conclusions:
- Specific lectins (ConA, WGA, PNA) and antibodies (ICAM1, pancytokeratin) are consistently expressed by normal pleural mesothelium.
- Absence of reactivity with markers like HPA, UEA-I, SBA, CEA, and HEA125 aids in identifying mesothelial cells.
- These findings support the confident identification of mesothelial cells in pleural effusions based on marker profiles.
Abstract:
20 specimens of normal pleural mesothelium were investigated with six lectins using isolated cells and tissue specimens as well as two different fixation techniques (glutaraldehyde and formaldehyde) and 10 monoclonal antibodies (MAb) on cytologic preparations only. Lectin binding sites for ConA, WGA, and PNA were present in all cases, whereas binding sites for the lectins HPA, SBA, and UEA-I could never be found. There was no staining difference with the two preparation and fixation techniques proving that they may be used to compare directly histologic and cytologic studies. Ten of fourteen histologic specimens were positive for the blood group antigen Lewis(y), three of them were positive for the antigen Lewis(b), all fourteen specimens were negative for Lewis(a) and Lewis(x). In all cases, mesothelial cells expressed ICAM1 and pancytokeratin. The antibodies against EMA, CEA, CD24, CD15, CD20, CD5, and HEA125 showed no reaction in mesothelial cells. Because HPA, UEA-I, SBA as well as CEA and HEA125 react in a high percentage with adenocarcinomas, non reactive cells of pleural effusions negative with these markers may be confidentially considered to be mesothelial in origin.