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 cytogenetic conversion to diploid hematopoiesis was obtained, but after discontinuation of IFN a 50% relapse of t(5;21) mitoses was found, and treatment was resumed. There is some degree of consensus that the mechanism by which IFN-alpha suppresses the Ph+ clone in CML consists in the restoration of normal adhesion of CML progenitors to the marrow stroma, by preventing transcription of the BCR/ABL mRNA, and hence expression of the p210 tyrosine kinase. However, if the 'faulty adhesion' hypothesis, 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.