Evaluation of immunohistochemistry using two different antibodies and procedures for primary lung adenocarcinoma harboring anaplastic lymphoma kinase rearrangement

Rearrangements of anaplastic lymphoma kinase (ALK) have been recently identified in non-small cell lung carcinomas. Previous studies have revealed characteristic features, including adenocarcinoma histology and mucin production, in ALK-positive lung carcinoma. The present study evaluated immunohistochemistry (IHC) in ALK-positive lung carcinoma using two different antibodies, clone 5A4 and D5F3, and compared the results. On the basis of the aforementioned characteristic features, out of 359 primary lung carcinomas, the ALK status of 14 adenocarcinomas was screened using the intercalated antibody-enhanced polymer (iAEP) method with antibody 5A4, and this was compared with the ALK status obtained using rabbit monoclonal antibody D5F3 and fluorescence in situ hybridization for ALK. Eight cases were demonstrated to be ALK-positive by IHC. Seven cases exhibited ALK rearrangement, which was demonstrated by fluorescence in situ hybridization. The IHC for ALK obtained using D5F3 was comparable with that of the iAEP and exhibited low heterogeneity. This finding suggests that IHC for ALK could be useful in limited tissue samples, such as biopsy specimens or cytology, for the screening of ALK-positive lung carcinoma. In the present study, it was demonstrated that IHC with ALK monoclonal antibody D5F3 was useful for screening lung adenocarcinoma harboring ALK rearrangement.