Immunologic classification of childhood acute lymphocytic leukemia

Treatment of lymphoblastic lymphoma in adults

Lymphoblastic lymphoma (LBL) is a rare subtype of non-Hodgkin's lymphoma (NHL) with biological features similar to those of acute lymphoblastic leukaemia. In the majority of cases LBL shows a T-cell phenotype, and mediastinal tumours are the most frequent manifestation. Outcomes of LBL patients treated according to NHL or ALL-type regimens are reviewed. Since prophylaxis of CNS relapse and local recurrence emerged as important issues in the treatment of LBL the different options are discussed. Several studies have used autologous stem cell transplantation (SCT) in the primary treatment of LBL and results are reviewed. The analysis of published prognostic factors and models in LBL demonstrates that, at present, no convincing risk model is available for LBL treated according to contemporary intensive chemotherapy protocols. Therefore indications for SCT in first complete remission (CR) cannot be defined. Future prospects for improvement of treatment results in LBL include intensification of chemotherapy, definition of prognostic factors, evaluation of minimal residual disease and SCT in high-risk patients.

Single allelic C mu gene rearrangements in patients with T cell and undifferentiated leukemia

By using a panel of monoclonal antibodies in combination with conventional morphological and histochemical studies, seven leukemic patients were diagnosed as having T-cell lymphocytic leukemia (ALL) and three patients were classified as having acute undifferentiated leukemia (AUL). When genomic DNA from each patient was analysed by the Southern blot hybridization technique, two out of seven cases with T-cell ALL and two of three cases with AUL demonstrated immunoglobulin (Ig) mu gene rearrangements. Interestingly, the patterns of C mu gene rearrangement found in these four cases as well as in the T-cell line HSB-2 were quite similar with rearrangement of a single allele and germ line configuration retained in the other allele. Ig gene rearrangement is an essential property of cells of B-lineage, but detection of an Ig gene rearrangement by itself seems insufficient to assign commitment to B-lineage differentiation. The significance of Ig gene rearrangements in T-cell ALL is unclear, but this heterogeneity at the DNA level among T-cell ALL may reflect differences in leukemogeneis and have prognostic and therapeutic implications.

Phenotypic heterogeneity at the DNA level in childhood leukemia with a mediastinal mass

Although phenotypic heterogeneity of childhood T-cell acute lymphocytic leukemia (T-ALL) which bear receptors for sheep red blood cells (E-rosettes) and/or T-cell-associated antigens has been reported, there are certain clinical features which are shared by most patients. A mediastinal mass is one of the most characteristic presentations in this particular disorder. This report describes four children with ALL, who presented with a mediastinal mass. Three patients were E-rosette-negative and one was E-rosette-positive. Individual surface phenotypes, defined by a panel of monoclonal antibodies, were quite different. Since Ig gene organization is an essential property of cells of B-lineage, it was surprising to find that analysis of genomic DNA revealed immunoglobulin (Ig) gene rearrangements in two of them. These findings suggest that there is significant heterogeneity even among those leukemias associated with a mediastinal mass, and that a mediastinal mass may not clearly indicate origin from cells of T-lineage. This heterogeneity may reflect differences in leukemogenesis and may have prognostic and therapeutic implications.

Phenotypic and ultrastructural characterization of a medullary thymocyte acute lymphoblastic leukemia with cellular procoagulant activity

The phenotypic and ultrastructural characterization of the blast cells from a T-cell acute lymphoblastic leukemia (T-ALL) that was associated with disseminated intravascular coagulation (DIC) is described. The bone marrow blasts were considered to represent neoplastic medullary thymocytes and were acid phosphatase (+), terminal deoxynucleotidyl transferase (-), acid alpha-naphthyl acetate esterase (-), E-rosette (+) at 4 degrees C and 37 degrees C, Fc- and C3-receptor (-), and cALLA-, Ia-, 9.6+, OKT3+, OKT4+, OKT6+/-, OKT8+, OKT10+. On transmission electron microscopic study, the predominant cell was 6 micron in diameter and possessed an irregular nucleus, moderate-sized nucleolus, marginated heterochromatin, abundant Golgi elements and granules, and prominent intermediate filaments. The cells were analyzed with normal and factor-deficient human plasmas and contained significant amounts of tissue factor-like procoagulant activity. This is the first report of a well-characterized medullary thymocyte T-ALL in which DIC was an accompanying feature, and the first demonstration of tissue factor-like procoagulant activity in acute lymphoblastic leukemia. In view of thrombohemorrhagic phenomena observed in association with other medullary thymocyte leukemias, these findings suggest that tissue factor-like procoagulant activity may be a characteristic of medullary thymocyte-derived lymphoid leukemias.

Enumeration of cytoplasmic mu immunoglobulin positive acute lymphoblastic leukemia cells by flow cytometry: comparison with fluorescence microscopy

The pre-B phenotype of childhood acute lymphoblastic leukemia, in which the mu immunoglobulin molecule is expressed in the cytoplasm of the blast cells, has been shown to have independent prognostic significance. Patients with this phenotype of the disease tend to have a poorer outcome on contemporary treatment regimens than do those with the other B-precursor phenotypes. For these clinical studies, the detection of the pre-B phenotype has depended upon fluorescent-microscope based techniques. A flow-cytometry based technique for the detection of the cytoplasmic mu immunoglobulin molecule is presented here and the results compared in detail with those of fluorescent microscopy. The results show that the two techniques are equivalent. The flow cytometry method has the advantage of a standardized control, is less labor intensive, and is observer-independent.

Purine metabolism in relation to leukemia and lymphoid cell differentiation

A number of inborn errors of purine metabolism have been associated with immunodeficiency diseases. From studies to the possible mechanism(s) leading to the defects in the immune system, it appeared that the accumulation of deoxyATP and deoxyGTP and the subsequent inhibition of ribonucleotide reductase played an important role. The inhibition of methylation pathways through the accumulation of s-adenosylmethionine seems to be a second valid concept. The amount to which certain subtypes of lymphoid cells were affected by the enzyme deficiencies was strongly related to the enzymatic make-up of the cells. Lymphoid cells from different maturation stages could be affected in a specific way, depending on the different enzyme activities of these cells. Studies on human lymphoblastic leukemias showed that, related to the immunological subtype, the different leukemias could be characterized by a different enzymatic make-up. In this paper we discuss the possibilities for a specific enzyme directed chemotherapy, directed against specific subtypes of human lymphoblastic leukemias. Experimental evidence indicates that for example the adenosine deaminase inhibitor 2'deoxycoformycin can be used as a specific drug against acute lymphoblastic leukemia with the T cell phenotype.