A strategy for demonstrating the clonal origin of small numbers of T lymphocytes in histopathological specimens

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Abstract
A strategy is described for detecting large T‐cell clones among small numbers of lymphoid cells in fresh or formalin‐fixed tissue samples using the polymerase chain reaction (PCR) to amplify and identify rearrangements of the V and J genes of the T‐cell gamma receptor. Following hybridization of primers with gene‐specific sequences at judiciously selected locations on each of the eight potentially active V and five potentially active J genes, the PCR can theoretically amplify DNA segments which span the join between rearranged V and J genes and are of approximately 384 different sizes, each segment size reflecting different gamma gene clonal rearrangements. Large monoclonal populations of T lymphocytes, indicated by excessive amounts of particular PCR segment sizes, can be further characterized by direct nucleotide sequencing of the hypervariable N regions of these segments, and the presence of such clones can be confirmed directly in tissue sections by in situ hybridization with N region‐specific oligonuclcotide probes.