Acquired amegakaryocytic thrombocytopenia associated with proliferation of gamma/delta TCR+ T-lymphocytes and a BCR-ABL (p210) fusion transcript

Abstract

Acquired amegakaryocytic thrombocytopenia (AATP) in adults is a rare disorder characterized by severe thrombocytopenia and decreased or absent megakaryocytes in an otherwise normal bone marrow. We present a 44-yr-old man in whom the diagnosis of AATP was established in January 2001. Immunophenotyping of the peripheral blood lymphocytes showed a relative increase in the subpopulation of gamma/delta T-cell receptor (TCR) positive (gamma/delta TCR+) and (CD4, CD8) negative T lymphocytes, and PCR suggested a monoclonal pattern of TCR gamma chain gene rearrangement. Cytogenetic examination of his bone marrow cells showed a normal male karyotype but RT-PCR analysis revealed a BCR-ABL (p210) fusion transcript. The inhibition of CFU-Mk growth mediated by the patient's T lymphocytes indicated that the pathogenic mechanism for AATP could be an immunological attack on megakaryocyte progenitors where the gamma/delta TCR-positive T lymphocytes are directly involved. The case emphasizes the complex association of T-lymphocyte monoclonal proliferation and AATP.