Diagnostic Value of protocadherin 15 on NK/T Cell Lymphoma

Objective: NK/T cell lymphoma is a unique subtype of non-Hodgkin’s lymphoma, accounting for 5% to 15% of lymphomas, and shows a prediction for the crowd of Asia, central and South America. Nasal, nasopharynx and oropharynx regions are commonly involved. Lesions may also occur in the upper respiratory tract, gastrointestinal tract, testis and other parts. Diagnosis of NK/T cell lymphoma is dependent on the pathological study of lesion biopsy specimens. Nevertheless, poor quantity or quality of specimens, such as tissue extensive necrosis often become an obstacle to the early diagnosis. Therefore, investigating an easy sampling, accurate and stable experimental marker has profound clinical significance for the diagnosis of NK / T-cell lymphoma.

Protocadherin15 (PCDH15) is a member of the cadherin family, which encoding gene located on chromosome 10q21-22. Rouget-Quermalet found a secreted isoform PCDH15 in the cracking sediment of human YT-type NK/T-cell lymphoma cell lines 8 years ago. PCDH15 was found not expressed in fresh or activated normal peripheral blood cells, CD4/CD8 positive lymphocytes, NK cells, normal spleen, lymph nodes, tonsils reactivity and CD34 + cord blood cells, only specifically expressed in three kinds of NK cell lymphoma cell lines. PCDH15 was not expressed in the biopsies of diffuse large B-cell lymphoma, mantle cell lymphoma and other types of lymphoma, but specifically expressed in NK/T lymphoma biopsy tissues.

Since PCDH15-SI was found in the human NK/T-cell lymphoma cell lines, its relationship with NK / T-cell lymphoma as well as other types of lymphoma was rarely reported, and studies of clinical specimens are still blank. The purpose of this study is to investigate what whether the PCDH15 is specifically expressed in NK/T-cell lymphoma biopsies, and whether the PCDH15-SI, as a secreted isoform, is specifically present in peripheral serum of newly diagnosed NK/T-cell lymphoma or not.

Materials and methods: 1. Screening biopsy paraffin blocks of NK/T-cell lymphoma(2010.1～2013.10) and non-NK/T-cell lymphoma(2012.10～2013.11) in West China Hospital of Sichuan University, which have 45cases and 33 cases stained by immunohistochemistry respectively and blank controls were set.

2. Collecting peripheral blood of NK/T-cell lymphoma, non-NK/T-cell lymphoma and normal population in the same Hospita. PCDH15 content of serum samples were detected by enzyme-linked immunosorbent content analysis (ELISA) method.

Results: 1. Results of immunohistochemistry showed that PCDH15 were expressed both in the experimental group NK/T-cell lymphoma and the control group with non-NK/T cell lymphoma. High expression rate in the NK/T-cell lymphoma group was higher than in non-NK/T cell lymphoma. The differences of PCDH15 expression levels between the two groups, or among the different anatomical structures were not statistically significant (P > 0.05).

2. PCDH15-SI can be detected in peripheral blood in the normal population, the experimental group of NK/T-cell lymphoma as well as in the control group of non-NK/T-cell lymphoma, which the level of PCDH15-SI in those patients with newly diagnosed disease was higher than that of the normal population and the serum level in the non-NK/T-cell lymphoma patients was higher than that in the NK/T-cell lymphoma patients(P < 0.05).

Conclusions: 1. PCDH15 was expressed in biopsies of different types of lymphoma, and the degree of expression in NK/T-cell lymphoma was significantly higher.

2. PCDH15 can’t be used to diagnose NK/T cell lymphoma as a marker.