T-cell activation-associated antigen expression by neoplastic T-cells.

Area of Science:

• Immunology
• Hematology
• Oncology

Background:

• T-cell neoplasms exhibit diverse clinicopathological and immunophenotypic features.
• Benign T cells express specific antigens in a hierarchical manner upon activation by phytohemagglutinin (PHA).

Purpose of the Study:

• To evaluate the expression of eight T-cell activation-associated antigens (T-AAgs) in various T-cell neoplasms.
• To compare T-AAg expression profiles in neoplastic T cells with those of PHA-activated benign T cells.

Main Methods:

• One- and two-color flow cytometry and/or immunohistochemistry were used.
• Eight T-AAgs (T10, T9, IL2-R, EMA, HLA-DR, LeuM1, Ki-1, and LeuM5) were assessed in 72 T-cell neoplasms.
• Immunophenotypic profiles were compared to those of in vitro PHA-activated normal T cells.

Main Results:

• 97% of T-cell neoplasms expressed at least one T-AAg, with expression patterns varying by clinicopathologic category.
• T-cell lymphoblastic malignancies uniformly expressed T10 and T9.
• Peripheral T-cell lymphomas (PTCLs) frequently expressed multiple T-AAgs (96%), often exceeding four.
• Only 26% of T-cell neoplasms displayed T-AAg profiles mirroring activated normal T cells.

Conclusions:

• T-AAg expression in T-cell neoplasms is common but does not typically replicate the hierarchical pattern seen in activated benign T cells.
• Neoplastic T cells may not represent direct malignant counterparts of activated normal T cells.
• T-AAg profiling offers insights into T-cell neoplasm biology and potential origins.