Immunophenotypically heterogeneous acute T-lymphoblastic leukemia has invariable immunogenotype: analysis of two cases.

Two patients with acute T-lymphoblastic leukemia showed heterogeneous expression of some immunophenotypic cell markers. Cell sorting was used to separate two CD34/CD117/TCRgammadelta and CD34/CD117/TCRgammadelta cell populations. The sorted TCRgammadelta population had more cells in S phase than the TCRgammadelta population. PCR analysis revealed identical TCR gene rearrangements in both populations. At relapse of one of the patients, only CD117, CD34, TCRgammadelta cells remained. The authors assume the presence of two immunophenotypically different cell subsets in different maturation stages at diagnosis.