Perforin and granzyme expression in cytotoxic T-cell lymphomas

Area of Science:

• Hematology
• Oncology
• Immunology

Background:

• Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of lymphoid malignancies.
• Cytotoxic T-cell lymphomas, characterized by CD8+ phenotype and expression of cytotoxic molecules like perforin and granzyme B, represent a distinct subset.
• Understanding the specific features and clinical behavior of CD8+ PTCLs is crucial for accurate diagnosis and treatment.

Purpose of the Study:

• To investigate the morphologic and immunohistochemical characteristics of CD8+ peripheral T-cell lymphomas (PTCLs).
• To compare the expression of cytotoxic molecules (perforin and granzyme B) in CD8+ PTCLs with other T-cell and NK-cell neoplasms.
• To evaluate the clinical course and associations of CD8+ PTCLs, including Epstein-Barr virus (EBV) involvement.

Main Methods:

• Morphologic and immunohistochemical analysis of 10 CD8+ PTCLs and comparison with 92 other T-cell and NK-cell neoplasms.
• Assessment of cytotoxic molecules (perforin and granzyme B) expression using immunohistochemistry.
• Detection of Epstein-Barr virus mRNA via in situ hybridization and apoptosis via TUNEL assay.

Main Results:

• CD8+ PTCLs were found to be rare (10 of 98 PTCLs studied), with most cases expressing perforin and granzyme B.
• These lymphomas frequently involved extranodal sites, particularly the skin, and exhibited an aggressive clinical course with a high 1-year mortality rate.
• Epstein-Barr virus mRNA was detected in a subset of cases, and all cases showed evidence of apoptosis.

Conclusions:

• CD8+ PTCLs are distinct, rare neoplasms of mature cytotoxic T lymphocytes with an aggressive clinical behavior.
• They often present with extranodal involvement and are associated with Epstein-Barr virus.
• These findings differentiate CD8+ PTCLs from other cytotoxic T-cell neoplasms like anaplastic large cell lymphomas (ALCLs).