ALTERATIONS OF T-CELL REPERTOIRE AFTER BONE-MARROW TRANSPLANTATION - CHARACTERIZATION OF OVER-REPRESENTED SUBSETS

We recently demonstrated that frequencies of T cell receptor-V (TcR-V) -specific subsets are frequently altered after both allogeneic and aut ologous BMT. The data reported here describe several characteristics o f altered T cell subsets: (i) their capacity to endure peripherally, ( ii) their correspondence to clonal donor T cell subsets, (iii) the ori gin of the clone (in one case amenable to analysis) from a mature T ce ll and not from new lymphopoiesis, and (iv) the presence of such a clo ne throughout a year of follow-up in a patient with chronic graft-vers us-host disease (GVHD) in whom it represented up to 1/10th of CD3(+) p eripheral blood lymphocytes (PBL) and was found to be host-reactive. T aken together, these findings provide direct evidence for the oligoclo nality of a large proportion of the peripheral T cell repertoire in pa tients subsequent to bone marrow transplantation, possibly accounting for their frequent depressed immune status. Moreover, the anti-host re activity demonstrated in a clone from the patient with chronic GVHD st rongly suggests that an oligoclonal response can be linked to a pathol ogical process.