Phenotypic and genotypic heterogeneity of peripheral T-cell lymphoma

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Abstract
A series of 21 phenotypically characterized T-cell lymphomas histologically defined as lymphocytic, lymphoblastic, immunoblastic, AILD type, pleomorphic, T-zone and Lennert''s T-cell lymphoma, were investigated for T-cell receptor (TcR) and immunoglobulin (Ig) gene rearrangements. Phenotypic analyses of frozen sections and cell suspensions were heterogeneous and in many cases no single T-cell marker recognized all of the malignant cells. Data derived by staining with antibodies reactive with antigens in paraffin embedded tissue were consistent with T NHL in all cases except lymphoblastic lymphoma. TcR gene rearrangements were observed in lymphocytic, lymphoblastic and immunoblastic lymphoma, however, in the remaining 14 phenotypically and histologically defined peripheral T-cell lymphomas, 2 showed rearrangement of TcR.gamma. and .beta. genes consistent with T NHL and 2 showed Ig JH rearrangements only, suggestive of either reactive T-cell populations masking cryptic disease or presence of tumour populations with aberrant gene rearrangement and expression of T lineage antigens. No Ig or TcR gene rearrangements were found in the remaining 10 cases, in which morphologically identifiable tumour cells comprised 10-90% of the cell population. In 3/6 cases tested some CD3 positive cells failed to stain with WT31 or .beta.F1, monoclonal antibodies that recognize determinants on combined TcR.gamma..beta. or TcR.beta.-chains respectively. Whether these cases represent tumors arising from an undetermined cell of origin or polyclonal expansions of T-cells remains to be determined. Our results confirm the phenotypic heterogeneity of histologically defined peripheral T-cell lymphoma and indicate that in these particular histological subtypes gene rearrangement analysis can also yield heterogeneous results which may be unhelpful in determining cell lineage and clonality.