CLONAL CD5-POSITIVE B-LYMPHOCYTES IN MYELODYSPLASTIC SYNDROME WITH SYSTEMIC VASCULITIS AND TRISOMY-8

Bone marrow and peripheral blood from a myelodysplastic syndrome (MDS) patient with trisomy 8 and associated systemic vasculitis was investi gated for clonal lymphoid lineage involvement using simultaneous metap hase and interphase fluorescence in situ hybridization (FISH) and immu nocytochemistry with antibodies against CD13 (granulocytic), glycophor in A (GPA, erythroid), and the lymphocytic antigens CD3, CD5, CD20, an d CD22. Trisomy 8 was detected in 55% of CD13+, 40% of GPA+, 6% of CD5 +, and 5% of CD20/22+, but not in CD3+ cells, In a complementary exper iment using interphase FISH on bone marrow cells sorted by flow cytome try, 13% of CD5/CD39 double-positive cells (76% purity) were found to be trisomic, The results indicate the existence of a small CDS-positiv e B-lymphoid clone as part of the MDS process in this patient. Since C D5/19-positive cells have been proposed to be autoantibody producing, this finding might be a clue to the pathogenesis underlying the propen sity for MDS patients to develop immune-mediated complications.