Determination of T Cell Monoclonality in Non-Hodgkin's Lymphoma by Frozen Section Immunohistology

Abstract

Monoclonal antibodies (mAb) reactive with seven distinct T cell receptor (TcR) α/β variable region (V) families have become available. We investigated the potential utility of these mAb to establish T cell clonality (restrictive expression of one single V region family type) by frozen section immunohistology. We studied 40 non-Hodgkin's lymphomas (NHL) previously classified, immunophenotypically and genotypically by the South Western Oncology Group (SWOC) as 20 B and 20 T cell NHL. Frozen sections of each neoplasm were immunostained with the following mAb: β-VSa, β-VSb, β-V6a, β-V8a, β-V12a, α/β-Va and α-V2a. The large atypical lymphocytes of 18 of 20 T cell NHL showed no reactivity with the seven V region family mAb and only two showed exclusive immunoreactivity (one with anti-αV2a and the other with anti-βV6a). All large atypical B cells in the 20 B cell NHL were non-reactive with the V region family mAb and each of the 40 neoplasms disclosed no or a trace reactivity in small host T cells. The results show that clonality can be determined in only a small percentage of T cell NHL (Sensitivity 10%, specificity 100%). Therefore, until new mAb become available, genotypic analysis remains the most sensitive and reliable method to establish T cell clonality.

Key Words:

• T cell lymphomas
• clonality
• immunohistology
• TcR V region monoclonal Antibodies