CHRONIC CLONAL MYELOPROLIFERATIVE DISEASE-ASSOCIATED WITH A T(5-21) TRANSLOCATION - COMPLETE BUT TRANSIENT HEMATOLOGIC AND CYTOGENETIC REMISSION INDUCED BY INTERFERON-ALPHA

A patient with a chronic myeloproliferative disease associated with a 100% t(5;12) translocation was treated with 3 million U per day of IFN -alpha 2a. Besides being consistently Ph-negative, the search for BCR/ ABL hybrid transcripts by means of RT-PCR was also negative. Total cyt ogenetic conversion to diploid hematopoiesis was obtained, but after d iscontinuation of IFN a 50% relapse of t(5;21) mitoses was found, and treatment was resumed. There is some degree of consensus that the mech anism by which IFN-alpha suppresses the Ph+ clone in CML consists in t he restoration of normal adhesion of CML progenitors to the marrow str oma, by preventing transcription of the BCR/ABL mRNA, and hence expres sion of the p210 tyrosine kinase. However, if the 'faulty adhesion' hy pothesis, and its correction by IFN-alpha, is to be considered correct , this case proves that it must include also Ph-negative, not BCR-ABL rearranged clonal myeloid proliferations.