Radiol Oncol 2002; 36(2): 183-4.
Immunohistochemical analysis of cathepsin B and cathepsin S in tumors, parenchyma and regional lymph nodes of the lung
Bernd Werle
Ruperta-Carola-University Heidelberg, Medizinische Klinik und Poliklinik, 69115 Heidelberg, Germany
Introduction                               red with those of cath B.2 Furthermore, the
expression of both cysteine-cathepsins was
correlated with clinical-pathological parameters of lung cancer patients.
The detection of antigens on tissue sections by using specific antibodies (immunohisto-chemistry (IHC)) is an important approach in identifying cell types, which express the specific antigens. Although the immunohistoche-mical analysis (IHA) is a relatively well established and simple method, the major problem remains to detect low concentrations of specific antigens. In this respect, the efforts are mainly focused on improved detection systems after binding of the specific primary antibody.
Cathepsin (cath) S is present at rather low levels in lung tissue extracts1, therefore low expression of cath S at the cellular level is expected. In fact, cath S was hardly detected by using standard procedures described in the literature. To solve this problem we established a highly sensitive staining protocol based on the CSA detection system from DAKO (Hamburg, Germany) in combination with antigen retrieval approach.
Material and methods
In order to identify cell populations producing cath S, we performed IHC on tissue sections deriving from formalin-fixed, paraffin-embedded tumors (n=36), non-tumors parenchyma (n=6) and regional lymph nodes of the lung (n=10). In addition, the expression of cath S in lung cell populations was compa-
Results
Cath S is expressed in alveolar type II cells, macrophages, bronchial epithelial cells and lymphocytes. The enzyme showed a lysoso-mal distribution over the cytoplasm. In addition, we observed differences in the staining intensity of cath S in macrophages, alveolar type II cells and lymphocytes, as well. In some bronchial epithelial cells a more restricted localization in the basal proliferating zone of the epithelium was observed. Immune reactive cath S was not found in alveolar type I cells. However, cath S could also be detected in lung tumors, independently of their origin. We found a positive reaction in adenocarci-nomas, squamous cell carcinomas and small cell carcinomas. Remarkably, a weak positive reaction at sides of interaction between tumor cells of the small cell carcinoma and the extracellular matrix of the alveoli could be observed. It should be noted that also in alveolar duct cells a focal positive reaction was visible.
Cath B could easily be detected using a standard protocol in combination with the ABC-system (Vector Laboratories, Serva Heidelberg), but without the need of an additional enhancing step. This clearly indicates that
184
Werle B / Immunohistochemical analysis of cathepsins
cath B is expressed at much higher levels in various cell populations compared with cath S. Cath B could also be detected in alveolar type II cells, macrophages, bronchial epithelial cells and various tumors. In contrast to cath S, we were not able to localize cath B in lymphocytes. The expression of cath S did not correlate with clinical-pathological parameters of lung cancer patients, while for cath B SpN1/PnP/pN3 primary tumors were more frequently labelled than PnP tumors.
Conclusion
We established a highly sensitive IHC protocol for the detection of cath S in tissue sections deriving from tumors, parenchyma and regional lymph nodes of the lung. Our results
show that of the two cysteine cathepsins (B and S), only cath S seems to be produced by lymphocytes, This indicates that cath S may be involved in regulatory mechanisms of the immune response.
References
1.   Werle B, Staib A, Jülke B, Ebert W, Zladoidsky, P, Sekirnik A, Kos J, Spiess E. Fluorometric microas-says for the determination of cathepsin L and ca-thepsin S activities in tissue extracts. Biol Chem 1999; 380: 1109-16.
2.   Werle B, Lötterle H, Schanzenbšcher U, Lah TT, Kalman E, Kayser K, Bülzebruck H, Schirren J, Krasovec M, Kos J, Spiess E.. Immunochemical analysis of cathepsin B in lung tumors: an independent prognostic factor for squamous cell carcinoma patients. Brit J Cancer 1999; 81: 510-9.
Radiol Oncol 2002; 36(2): 183-4.