CLONAL LYMPHOCYTES ARE DETECTABLE IN ONLY SOME CASES OF MDS

Clonal analysis of lymphocytes from patients with myelodysplastic syndrome (MDS) has been carried out using X-chromosome inactivation patterns detected by the probe M27-beta, and by polymerase chain reaction amplification of the immunoglobulin heavy chain gene hypervariable region, CDR3. Of 32 female patients heterozygous for M27-beta only seven (22%) demonstrate monoclonality of peripheral blood lymphocytes. 12 (37%) give unequivocal polyclonal results and the remaining cases give patterns of X-inactivation which cannot be interpreted either way. A study of 68 MDS patients showed five (7%) with a population of B-cells with a monoclonal rearrangement of CDR3 compared with none out of 60 normal individuals, none out of 15 with B-non Hodgkin lymphoma (B-NHL) in remission and 19 out of 25 (75%) of cases of B-chronic lymphocytic leukaemia (B-CLL). Monoclonal lymphocytes were found by both techniques in only two females with MDS. We conclude that the presence of polyclonal lymphocytes is a common finding in patients with MDS.