Introduction: Hodgkin's disease is a common B-cell neoplasm. One of the peculiarities of this lymphoma is that the actual tumor cells, the large Hodgkin-Reed-Sternberg (HRS) cells, constitute only a minor fraction of the tumor mass among a major population of non-neoplastic cells that consists mostly of T cells. These T cells typically form rosettes around the HRS cells and express CD4 as well as CD45RO and activation markers in most cases. The question we want to adress is whether there is specific recognition by these T cells of peptides presented by the HRS cells. In this case the rosetting T cells might be oligoclonal and express a restricted receptor repertoire.Material and Methods: We therefore have established a single cell PCR system that allows amplification of TCR beta gene rearrangements from single human T cells. In this semi-nested PCR the reaction mix for each cell contains 23 V and 7 J beta specific primers in the first of two rounds of amplification. The method was established on single cells sorted into PCR tubes by FACS and was then extended to single cells obtained from frozen tissue sections by micromanipulation.Results: Single T cells that were found in direct physical contact with HRS cells were micromanipulated from frozen sections of Hodgkin's lymphoma tissue and transferred to PCR tubes. TCR beta gene rearrangements were amplified from these cells. We are currently in the process of sequencing the PCR products and analyzing the sequences for signs of antigenic selection.