Shifts in expression of immunological cell markers in relapsed acute leukemia

The immunophenotypic features of leukemia blast cells were analyzed in a gr oup of 156 patients with different immunological subtypes of acute leukemia , both lymphoblastic and myeloblastic. Of the 58 patients for whom immunolo gic studies were performed at relapse, 42 (72%) showed changes in the expre ssion of immunologic markers. The minor shifts in B-ALL were observed most frequently and concerned of the loss of CD34 antigen in 17 cases and the lo ss of cALLA (CD10) in 7 cases of B-ALL at the first relapse. The acquisitio n of cell markers was not frequently observed, only in four cases could be seen. HLA-DR molecules remained relatively constant from diagnosis to relap se. In 2 from 3 T-ALL cases the loss of CD1 and CD2 markers, respectively, was noticed at relapse. CD5 and CD7 markers were relatively stable. In AML cases at relapse the acquisition of CD13 marker (in 4 from 7 cases) was oft en observed. It was interesting that comparing to the B-ALL cases, the loss of CD34 marker in AML cases was stray. In one case the acquisition of this antigen at relapse was actually observed. The major interlineage shift was detected in one case of B-ALL, that was newly diagnosed at relapse as AML M4 and presented different cytogenetic features. This case provides strong connection with the treatment, as more recently epipodophyllotoxins (vumon in our patient) have been linked to the development of secondary AML associ ated with a shorter latency period. The immunophenotypic changes frequently occur at relapse in all acute leuke mia types. The shifts (loss or acquisition) in expression of individual mar kers at relapse are bound with the first diagnosis and may have a relations hip to the treatment and are important for correct assessment of minimal re sidual disease.