SEQUENTIAL IMMUNOPHENOTYPIC ANALYSIS OF MAST-CELLS IN A CASE OF SYSTEMIC MAST-CELL DISEASE EVOLVING TO A MAST-CELL LEUKEMIA

The immunophenotypic characteristics of both bone marrow (BM) and peri pheral blood (PB) mast cells (MC), from a patient suffering from an ag gressive systemic mast cell disease (SMCD), were sequentially analyzed by flow cytometry using direct immunofluorescence. Analysis was carri ed out at diagnosis, during clinical response induced by interferon al fa-2h/prednisone therapy, and later at relapse. Our results show that together with the CD117 and IgE characteristic markers, at diagnosis B M MC showed strong expression of CD11c, CD13, CD29, CD33, CD44, CD45, CD63, and CD71, and they were also positive for CD2, CD22, CD25, and C D54 although at a lower level. PB MO displayed similar immunophenotypi c characteristics although they had a lower expression of CD11c, CD25, CD33, CD63, CD69, and CD71 with a higher reactivity for CD117. Unlike BM MC, PB MC were weakly positive for CD41a and CD61. Sequential stud ies showed decreased numbers of both BM and PB MC during clinical resp onse associated with a higher expression of the CD29 and CD54 adhesion molecules. In turn, clinical relapse was related to increased numbers of PB and BM MC together with lower CD2, CD11c, CD45, and CD54 expres sion and a higher reactivity for the CD117 and CD25 antigens. CD2 had become negative at the last follow-up study. In addition, an increased proportion of S-phase MC was observed at relapse. These findings sugg est that the assessment of the quantitative expression of cell-adhesio n molecules and growth-factor receptors together with cell cycle studi es of mast cells could be of value for monitoring therapy and predicti ng clinical outcome in aggressive SMCD. (C) 1997 Wiley-Liss, Inc.